Big Ideas Math Answers Grade 1 Chapter 5

Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20

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Big Ideas Math Book 1st Grade Answer Key Chapter 5 Subtract Numbers within 20

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Vocabulary

Lesson: 1 Count Back to Subtract within 20

Lesson: 2 Use Addition to Subtract within 20

Lesson: 3 Subtract 9

Lesson: 4 Get to 10 to Subtract

Lesson: 5 More True or False Equations

Lesson: 6 Make True Equations

Lesson: 7 Problem Solving: Subtraction within 20

Chapter 5 Subtract Numbers within 20

Chapter 5 Subtract Numbers within 20 Vocabulary

Organize It

Review Words:
bar model
difference
minus
part-part-whole model
subtraction equation

Use the review words to complete the graphic organizer.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 1
Answer:

Explanation:
Given 8 – 3 = 5, Here – represents minus sign minus
represents the arithmetic operation of subtraction between
two numbers, 5 represents difference is the result of subtracting
one number from another and 8 – 3 = 5 is called subtraction equation
 is a statement that shows a subtraction operation using the minuend,
subtrahend, difference.

Define It

Match the review word to its definition.

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 2
Answer:

Explanation:
In the above picture, the first one is a bar model  a pictorial representation
of a problem or concept where bars or boxes are used to represent the
known and unknown quantities, the second picture is the part-part-whole model
is a simple pictorial representation of a problem that helps us
see the relationships between numbers.

Lesson 5.1 Count Back to Subtract within 20

Explore and Grow

Model the story.

You are on floor number 12. You go down 4 floors. What floor are you on now?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 3

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 4

floor number ____8______
Answer:

I am in 8 floors now.

Explanation:
Given I am on floor number 12 and go down 4 floors means
now I am on floor 12 – 4 = 8 . on the number line we start from 12
since subtracting makes numbers smaller, we move left to subtract.
So from 12 we move 4 parts back or left to 8. Therefore now I am at
8 floor now.

Show and Grow

Question 1.
15 – 8 = ___7____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 5
Answer:

15 – 8 = 7

Explanation:
We subtract 15 – 8 = 7, on number line we start at 15 and
move 8 steps back or left we get 7.

Question 2.
12 – 3 = ___9______
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

12- 3 = 9

Explanation:
We subtract 12 – 3 = 9, on number line we start at 12 and
move 3 steps back or left we get 9.

Question 3.
17 – 9 = ____8_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

17 – 9 = 8

Explanation:
We subtract 17 – 9 = 8, on the number line we start at 17 and
move 9 steps back or left we get 8.

Apply and Grow: Practice

Question 4.
11 – 6 = ____5____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

11 – 6 = 5

Explanation:
We subtract 11 – 6 = 5, on the number line we start at 11 and
move 6 steps back or left we get 5.

Question 5.
13 – 7 = ___6_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

13 – 7 = 6

Explanation:
We subtract 13 – 7 = 6, on the number line we start at 13 and
move 7 steps back or left we get 6.

Question 6.
18 – 9 = ___9_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

18- 9 = 9

Explanation:
We subtract 18 – 9 = 9, on number line we start at 18 and
move 9 steps back or left we get 9.

Question 7.
20 – 10 = ____10_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

20 – 10 = 10

Explanation:
We subtract 20 – 10 = 10, on the number line we start at 20 and
move 10 steps back or left we get 10.

Question 8.
17 – 8 = ____9_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

17- 8 = 9

Explanation:
We subtract 17 – 8 = 9, on the number line we start at 17 and
move 8 steps back or left we get 9.

Question 9.
18 – 3 = ____15______
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

18 – 3 = 15

Explanation:
We subtract 18 – 3 = 15, on the number line we start at 18 and
move 3 steps back or left we get 15.

Question 10.
___12____ = 16 – 4
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

16- 4 = 12

Explanation:
We subtract 16 – 4 = 12, on the number line we start at 16 and
move 4 steps back or left we get 12.

Question 11.
___6_____ = 14 – 8
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 6
Answer:

14- 8 = 6

Explanation:
We subtract 14 – 8 = 6, on the number line we start at 14 and
move 8 steps back or left we get 6.

Question 12.
DIG DEEPER!
Write the equation shown by the number line.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 7
___15_____ – __9______ = ___6_____
Answer:
The equation on the number line is 15 – 9 = 6.

Explanation:
As shown on the number line we start at 15 and move
9 steps or 9 units back or left we reached at 6 so the equation shown by the number line is 15 – 9 = 6.

Think and Grow: Modeling Real Life

You collect 6 gems. Your friend collects 14. How many fewer gems do you collect?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 8
Model:

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 9
Subtraction equation:

____8____ fewer gems

Subtraction equation is 14 – 6 = 8,
I have 8 fewer gems.

Explanation:
Given I have collected 6 gems and friend collects 14 gems
now how many less or fewer gems I have than my friend are
14 – 6 = 8 gems, On number line we start at 14 and
move 6 steps or 6 units back or left we reach at 8.
So the Subtraction equation is 14 – 6 = 8,
I have 8 fewer gems.

Show and Grow

Question 13.
Your friend finds 16 gold bars. You find 9. How many fewer gold bars do you find?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 10
Model:

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 11
Subtraction equation:

_____7_____ gold bars
Answer:

Subtraction equation is 16 – 9 = 7,
I have 7 fewer gold bars.

Explanation:
Given friend finds 16 gold bars and I found 9,
now how many less or fewer gold bars I have than my friend are
16 – 9 = 7 gold bars, On number line we start at 16 and
move 9 steps or 9 units back or left we reach at 7.
So the Subtraction equation is 16 – 9 = 7,
I have 7 fewer gold bars.

Count Back to Subtract within 20 Practice 5.1

Question 1.
12 – 5 = __7____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

12 – 5 = 7

Explanation:
We subtract 12 – 5 = 7, on number line we start at 12 and
move 5 steps back or left we get 7.

Question 2.
15 – 7 = ____8____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

15 – 7 = 8

Explanation:
We subtract 15 – 7 = 8, on number line we start at 15 and
move 7 steps back or left we get 8.

Question 3.
13 – 6 = ___7_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

13 – 6 = 7

Explanation:
We subtract 13 – 6 = 7, on number line we start at 13 and
move 6 steps back or left we get 7.

Question 4.
14 – 5 = ___9_______
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

14 – 5 = 9

Explanation:
We subtract 14 – 5 = 9, on number line we start at 14 and
move 5 steps back or left we get 9.

Question 5.
11 – 5 = ____6______
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

11- 5 = 6

Explanation:
We subtract 11 – 5 = 6, on number line we start at 11 and
move 5 steps back or left we get 6.

Question 6.
15 – 4 = ___11_____
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

15- 4 = 11

Explanation:
We subtract 15 – 4 = 11, on number line we start at 15 and
move 4 steps back or left we get 11.

Question 7.
__10____ = 18 – 8
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

18 – 8 = 10

Explanation:
We subtract 18 – 8 = 10, on number line we start at 18 and
move 8 steps back or left we get 10.

Question 8.
____4_____ = 12 – 8
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 12
Answer:

12 – 8 = 4

Explanation:
We subtract 12 – 8 = 4, on number line we start at 12 and
move 8 steps back or left we get 4.

Question 9.
DIG DEEPER
Write the equation shown by the number line.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 13
___14_____ – ___9_____ = ___5_____
Answer:

The equation on the number line is 14 – 9 = 5.

Explanation:
As shown on the number line we start at 14 and move
9 steps or 9 units back or left we reach at 5, so the
equation shown by the number line is 14 – 9 = 5.

Question 10.
Modeling Real Life
You play soccer. The visiting team scores 12 goals. Your team scores 4 fewer. How many goals does your team score?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 14

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 15

_____8_____ goals
Answer:

Subtraction equation is 12 – 4 = 8,
My team scored 8 goals

Explanation:
Given visiting team scores 12 goals, My team scores 4 fewer goals
My team have scored 12 – 4 = 8 goals, On number line we start at
12 and move 4 steps or 4 units back or left we reach at 8.
So the Subtraction equation is 12 – 4 = 8,
therefore my team score 8 goals.

Review & Refresh

Question 11.
6 + 2 = ___8_____
Answer:
6 + 2 = 8

Explanation :
The addition equation is 6 + 2 = 8,
We add 2 to 6 we get 8.

Question 12.
4 + 3 = ___7_____
Answer:
4 + 3 = 7

Explanation :
The addition equation is 4 + 3 = 7,
We add 3 to 4 we get 7.

Question 13.
8 + 2 = ___10____
Answer:
8 + 2 = 10

Explanation :
The addition equation is 8 + 2 = 10,
We add 2 to 8 we get 10.

Question 14.
5 + 4 = ____9___
Answer:
5 + 4 = 9

Explanation :
The addition equation is 5 + 4 = 9,
We add 4 to 5 we get 9.

Lesson 5.2 Use Addition to Subtract within 20

Explore and Grow

Model the story.
Your class needs to make 15 scrapbook pages. 8 are already made. How many more pages does your class need to make?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 16

Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 17

____7_____ more pages

15 – 8 = 7,
We need 7 more pages to make.

Explanation:
Given my class needs to make 15 scrapbook pages,
8 are already made ,We need 15 – 8 = 7 more pages
are needed  to make scrapbook.

Show and Grow

Question 1.
11 – 7 = ?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 18
Think 7 + ___4____ = 11.
So, 11 – 7 = ___4____ .
Answer:

7 + 4 = 11
11 – 7 = 4

Explanation:
Explanation:
First we move from 7 on number line and start moving till
11 we count how many units right we have moved we get
4 units so 7 + 4 = 11 or we start at 11 on number line and
move 7 steps back or left we get 4, 11 – 7 = 4.

Question 2.
16 – 8 = ?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
Think 8 + ___8____ = 16.
So, 16 – 8 = ___8____ .
Answer:

8 + 8 = 16
16 – 8 = 8

Explanation:
First we move from 8 on number line and start moving till
16 we count how many units right we have moved we get
8 units so 8 + 8 = 16 or we start at 16 on number line and
move 8 steps back or left we get 8, 16 – 8 = 8.

Question 3.
13 – 10 = ?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
Think 10 + __3_____ = 13.
So, 13 – 10 = ___3____ .
Answer:

10 + 3 = 13
13 – 10 = 3

Explanation:
First we move from 10 on number line and start moving till
13 we count how many units right we have moved we get
3 units so 10 + 3 = 13 or we start at 13 on number line and
move 10 steps back or left we get 3, 13 – 10 = 3.

Apply and Grow: Practice

Question 4.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
12 – 7 = ?
Think 7 + ___5____ = 12.
So, 12 – 7 = ___5____ .
Answer:

7 + 5 = 12
12 – 7 = 5

Explanation:
First we move from 7 on number line and start moving till
12 we count how many units right we have moved we get
5 units so 7 + 5 = 12 or we start at 12 on number line and
move 7 steps back or left we get 5, 12 – 7 = 5.

Question 5.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
17 – 8 = ?
Think 8 + ___9____ = 17.
So, 17 – 8 = __9____ .
Answer:

8 + 9 = 17
17 – 8 = 9

Explanation:
First we move from 8 on number line and start moving till
17 we count how many units right we have moved we get
9 units so 8 + 9 = 17 or we start at 17 on number line and
move 8 steps back or left we get 9, 17 – 8 = 9.

Question 6.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
11 – 2 = ___9_____
Answer:

11 – 2 = 9

Explanation:
We subtract 11 – 2 = 9, on number line we start at 11 and
move 2 steps back or left we get 9.

Question 7.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 19
_____14____ = 19 – 5
Answer:

19 – 5 = 14 or 14 = 19 – 5

Explanation:
We subtract 19 – 5 = 14, on number line we start at 19 and
move 5 steps back or left we get 14.

Question 8.
DIG DEEPER!
Tell what subtraction problem Newton and Descartes solved. Think: What strategies did they use?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 20
Answer:
Newton and Descartes solved the subtraction equation as
First  by 5 + = 13
Second by 13 – 5 =_

Explanation :
Newton and Descartes solved the subtraction equation on the number line
first they solved equation 5 + _______ = 13 as started from 5 and moved
8 units right reached till 13 so the missing number is 8, 5 + 8 = 13.
In second method they solved by starting from 13 and moved 5 units
left till they reached 8 on the number line so they solved
the subtraction equation as 13 – 5 = 8.

Think and Grow: Modeling Real Life

There are 15 people in an elevator. Some of them exit. There are 7 left. How many people exit?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 21
Model:

Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 22
Subtraction equation:
15 – 7 = 8

____8_____ people
Answer:

15 – 7 = 8,
8 people exit.

Explanation:
Given 15 people are there in elevator, some of them exit,
There are 7 left, So people exit are 15 – 7 = 8,
So 8 people exit from elevator.

Show and Grow

Question 9.
There are 18 people in a subway car. Some of them exit. There are 9 left. How many people exit?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 23
Model:

Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 22
Subtraction equation:
18 -9 = 9

_____9_____ people
Answer:

18 – 9 = 9,
9 people exit.

Explanation:
Given there are 18 people in a subway car , some of them exit,
There are 9 left, So people exit are 18 – 9 = 9,
So 9 people exit from subway car.

Use Addition to Subtract within 20 Practice 5.2

Question 1.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 24
13 – 9 = ?
Think 9 + __4____ = 13
So, 13 – 9 = ___4____.
Answer:

9 + 4 = 13
13 – 9 = 4

Explanation:
First we move from 9 on number line and start moving till
13 we count how many units right we have moved we get
4 units so 9 + 4 = 13 or we start at 13 on number line and
move 9 steps back or left we get 4, 13 – 9 = 4.

Question 2.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 24
17 – 8 = ?
Think 8 + __9____ = 17
So, 17 – 8 = ___9____.
Answer:

8 + 9 = 17
17 – 8 = 9

Explanation:
First we move from 8 on number line and start moving till
17 we count how many units right we have moved we get
9 units so 8 + 9 = 17 or we start at 17 on number line and
move 8 steps back or left we get 9, 17 – 8 = 9.

Question 3.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 24
14 – 7 = ____7_____
Answer:

14 – 7 = 7

Explanation:
We subtract 14 – 7 = 7, on number line we start at 14 and
move 7 steps back or left we get 7.

Question 4.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 24
____13_____ = 17 – 4
Answer:

17 – 4 = 13

Explanation:
We subtract 17 – 4 = 13, on number line we start at 17 and
move 4 steps back or left we get 13.

Question 5.
DIG DEEPER!
Tell what subtraction problem Newton and Descartes solved. Think: What strategies did they use?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 25
Answer:
Newton and Descartes solved the subtraction equation as
First by 11 – 7 =_4 
Second  by 7 +  4  =  11

Explanation :
Newton and Descartes solved the subtraction equation on the number line
first method they solved by starting from 11 and moved 7 units
left till they reached 4 on the number line so they solved
the subtraction equation as 11 – 7 = 4.
Second they solved equation 7 + ______ = 11 as started from 7 and moved
4 units right reached till 11 so the missing number is 4, 7 + 4 = 11.

Question 6.
Modeling Real Life
There are 13 people on a train. Some of them exit. There are 6 left. How many people exit?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 26

Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 27

_____7_______ people
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-1

13 – 6 = 7,
So, 7 people exit.

Explanation:
Given there are 13 people on a train , some of them exit,
There are 7 left, So people exit are 13 – 6 = 7,
So 7 people exit from the train.

Review & Refresh

Question 7.
10 – 9 = ____1______
Answer:
10 – 9 = 1

Explanation :
The subtraction equation is 10 – 9 = 1,
We subtract 9 from 10 we get 1.

Question 8.
9 – 9 = ____0______
Answer:
9 – 9 = 0

Explanation :
The subtraction equation is 9 – 9 = 0,
We subtract  9 from 9 we get 0.

Lesson 5.3 Subtract 9

Explore and Grow

Use counters to find each difference.

Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 28

Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-2
Explanation:
To find 15 -10 =  here we use two counters  first
we take total 15 circles in that we strike 10 numbers
the left number of circles are 5, So 15 – 10 = 5.
To find 15 – 9 = here we use two counters and we take
15 circles in that we will strike out 9 numbers the left are
6, So 15 – 9 = 6.

Show and Grow

Get to 10 to subtract.

Question 1.
17 – 9 = ?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 29
17 – __7____ = 10
10 – ___2____ = ___8___
So, 17 – 9 = ___8_____
Answer:
17 – 7 = 10 we get 10
10 – 2 = 8,
So 17 – 9 = 8

Explanation:
We have 2 counters in counter one we have 10 circles
and in next counter we have 7 circles so in total we have 17,
First we see out of 17 if we consider counter-2 we have 7 strike outs
means 17 – 7 = 10 we got 10 in counter-1 and if we see first counter
we have 2 strike outs 10 – 2 = 8, So total number of circles strike out
from 2-counters are 7 + 2 = 9, So making equation as 17 – 9 = 8.

Question 2.
14- 9 = ?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 30
14 – __4____ = 10
10 – ___5____ = ___5___
So, 14 – 9 = _____5___
Answer:
14 – 4  = 10 we get 10
10 – 5 = 5
So 14 – 9 = 5

Explanation:
We have  2 counters in counter one we have 10 circles
and in next counter we have 4 circles so in total we have 14,
First we see out of 14 if we consider counter-2 we have 4 strike outs
means 14 – 4 = 10 we got 10 in counter-1 and if we see first counter
we have 5 strike outs 10 – 5 = 5,So total number of circles strike out
from 2-counters are 4 + 5 = 9, So making equation as 14 – 9 = 5.

Apply and Grow: Practice

Question 3.
16 – 9 = ?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 31
16 – ___6___ = 10
10 – ____3___ = __7____
So, 16 – 9 = ___7_____
Answer:
16 – 6 = 10 we get 10
10 – 3 = 7
So 16 – 9 = 7

Explanation:
We have  2 counters in counter one we have 10 circles
and in next counter we have 6 circles so in total we have 16,
First we see out of 16 if we consider counter-2 we have 6 strike outs
means 16 – 6 = 10 we got 10 in counter-1 and if we see first counter
we have 3 strike outs 10 – 3 = 7, So total number of circles strike out
from 2-counters are 6 + 3 = 9, So making equation as 16 – 9 = 7.

Question 4.
11 – 9 = ?
11 – ___1____ = 10
10 – ___8____ = ___2____
S0, 11 – 9 = ____2____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-3
11 – 1 = 10 we get 10
10 – 8 = 2
So 11 – 9 = 2

Explanation:
To solve 11 – 9  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 1 circle so in total we have 11,
Now in all we will strike 9 circles, 1 circle from counter-2 making equation
as 11 – 1 = 10 we got 10 in counter-1 and we strike out  8 circles from counter-1
we are left with 2 making it as 10 – 8 = 2, So in total we have taken 8 + 1 = 9
from 11 in 2-counters, making equation as 11 -9 = 2 as shown in the picture.

Question 5.
15 – 9 = ?
15 – __5_____ = 10
10 – __4______ = __6______
So, 15 – 9 = ___6_____
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-4
15- 5 = 10 we get 10
10 – 4 = 6
So 15 – 9 = 6

Explanation:
To solve 15 – 9  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 5 circles so in total we have 15,
Now in all we will strike 9 circles, 5 circles from counter-2 making equation
as 15 – 5 = 10 we got 10 in counter-1 and we strike 4 circles from counter-1
we are left with 6 making it as 10 – 4 = 6, So in total we have taken 5 + 4 = 9
from 15 in 2-counters, making equation as 15 -9 = 6 as shown in the picture.

Question 6.
MP Structure
Which models show 12 – 9?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 32
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-5 Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-6

First model and third model shows 12 – 9.

Explanation:
If we see all models are having 12 now we will see which model is subtracting 9,
For this we consider both counters and count total strike outs
Model 1 have 9 strike outs , Model 2 have 10 strike outs,
Model 3 have 9 strike outs, So first model and third model shows 12 – 9.

Think and Grow: Modeling Real Life

You have 12 eggs. You use 9 of them. How many eggs are left?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 33
Model:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 34
Subtraction equation:

___3_______ eggs
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-7
12 – 9 = 3,
So 3 eggs are left.

Explanation:
Given I have 12 eggs and use 9 eggs,
By using counters first I take total 12 circles then I strike out 9,
So left are 3 so the subtraction equation is 12 – 9 = 3,
So 3 eggs are left.

Show and Grow

Question 7.
An egg carton has 18 eggs. You crack 9 of them. How many eggs are not cracked?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 35
Model:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 34
Subtraction equation:

_____9_______ eggs
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-8
18 – 9 = 9,
So 9 eggs are not cracked.

Explanation:
Given egg carton has 18 eggs and crack 9 of them,
By using counters first I take total 18 circles then I strike out 9,
So left are 9 so the subtraction equation is 18 – 9 = 9,
So 9 eggs are not cracked.

Subtract 9 Practice 5.3

Get to 10 to subtract.

Question 1.
18 – 9 = ?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 36
18 – ___8_____ = 10
10 – __1_____ = __9_____
So, 18 – 9 = ____9_____ .
Answer:

18- 8 = 10 we get 10
10 – 1 = 9
So 18 – 9 = 9

Explanation:
To solve 18 – 9  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 8 circles so in total we have 18,
Now in all we will strike 9 circles, 8 circles from counter-2 making equation
as 18 – 8 = 10 we got 10 in counter-1 and we strike 1 circle from counter-1
we are left with 9 making it as 10 – 1 = 9, So in total we have taken 8 + 1 = 9
from 18 in 2-counters, making equation as 18 – 9 = 9 as shown in the picture.

Question 2.
12 – 9 = ?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 37
12 – ___2_____ = 10
10 – ___7____ = ___3____
So, 12 – 9 = _____3____ .
Answer:
12 – 2 = 10 we get 10
10 – 7 = 3
12 – 9 = 3

Explanation:
To solve 12 – 9  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 2 circles so in total we have 12,
Now in all we will strike 9 circles, 2 circles from counter-2 making equation
as 12 – 2 = 10 we got 10 in counter-1 and we strike 7 circles from counter-1
we are left with 3 making it as 10 – 7 = 3, So in total we have taken 2 + 7 = 9
from 12 in 2-counters, making equation as 12 – 9 = 3 as shown in the picture.

Question 3.
19 – 9 = ?
19 – ____9____ = 10
10 – ___0____ = ___10____
So, 19 – 9 = ____10_____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-9
19 – 9 = 10,
10 – 0 = 10
So, 19 -9 = 10

Explanation:
To solve 19 – 9  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 9 circles so in total we have 19,
Now in all we will strike 9 circles, 9 circles from counter-2 making equation
as 19 – 9 = 10 we got 10 in counter-1, we will not strike in counter-1 as we have
already taken 9 ,So 10 – 0 = 10, We are left with 10 and the equation is 19 – 9 = 10.

Question 4.
MP Structure
Which models show 16 – 9?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 38
Answer:

Second model and third model shows 16 – 9.

Explanation:
If we see all models are having 16 now we will see which model is subtracting 9,
For this we consider both counters and count total strike outs
Model 1 have 10 strike outs , Model 2 have 9 strike outs,
Model 3 have 9 strike outs, So Second model and third model shows 16 – 9.

Question 5.
Modeling Real Life
You have 14 water balloons. You break 9 of them. How many water balloons are left?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 39
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 40

____5______ Water balloons
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-10
14 – 9 = 5
5 water balloons are left.

Explanation:
Given I have 14 water balloons. I break 9 of them,
So I will take 2 counters counter-1 has 10 circles and counter-2 has
4 circles in all I have 14 number of circles, now over all I will
strike out 9 from the 2-counters. As counter-2 has only 4 I will take 5 from
counter-1 so that in total 4 + 5 = 9 circles are strike out so we are left with 5,
So the subtraction equation is 14  – 9 = 5, So 5 water balloons are left.

Review & Refresh

Question 6.
Use the picture to complete the number bond.
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 41
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-11

Explanation:
Number bonds are pictures that show the bond between parts and whole.
So here we know that 10 is the whole number
and 8 is one of the numbers from the pair of number bonds.
The other number that combines with 8 to give 10 is 2.

Lesson 5.4 Get to 10 to Subtract

Explore and Grow

Use counters to find the difference. Show how you can make a 10 to solve.

Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 42
Answer:

Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-12

14 – 4 = 10
10 – 2 = 8
14 – 6 = 8

Explanation:
To solve 14 – 6  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter we have 4 circles so in total we have 14,
Now in all we will strike 6 circles, 4 circles from counter-2 making equation
as 14 – 4 = 10 we got 10 in counter-1 and we strike 2 circles from counter-1
we are left with 8 making it as 10 – 2 = 8, So in total we have taken 4 + 2 = 6
from 14 in 2-counters, making equation as 14 – 6 = 8 as shown in the picture.

Show and Grow

Get to 10 to subtract.

Question 1.
12 – 5 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 43
12 – __2____ = 10
10 – __3___ = ___7_____
So, 12 – 5 = ____7______
Answer:

12 – 2 = 10 we get 10
10 – 3 = 7
12 – 5 = 7

Explanation:
To solve 12 – 2  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 2 circles so in total we have 12,
Now in all we will strike 5 circles, 2 circles from counter-2 making equation
as 12 – 2 = 10 we got 10 in counter-1 and we strike 3 circles from counter-1
we are left with 7 making it as 10 – 3 = 7, So in total we have taken 2 + 3 = 5
from 12 in 2-counters, making equation as 12 – 5 = 7 as shown in the picture.

Question 2.
17 – 8 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 44
17 – ___7___ = 10
10 – __1___ = ___9_____
So, 17 – 8 = ___9_______
Answer:
17 – 7 = 10
10 – 1 = 8
So 17 – 8 = 9

Explanation:
To solve 17 -8  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 7 circles so in total we have 17,
Now in all we will strike 8 circles, 7 circles from counter-2 making equation
as 17 – 7 = 10 we got 10 in counter-1 and we strike 1 circle from counter-1
we are left with 9 making it as 10 – 1 = 9, So in total we have taken 7 + 1 = 8
from 17 in 2-counters, making equation as 17 – 8 = 9 as shown in the picture.

Apply and Grow: Practice

Get to 10 to subtract

Question 3.
16 – 7 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 45
I6 – __6______ = 10
10 – ___1_____ = ____9____
So, 16 – 7 = _____9_____ .
Answer:
16 – 6 = 10
10 – 1 = 9
So 16 – 7 = 9

Explanation:
To solve 16 -7  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 6 circles so in total we have 16,
Now in all we will strike 7 circles, 6 circles from counter-2 making equation
as 16 – 6 = 10 we got 10 in counter-1 and we strike 1 circle from counter-1
we are left with 9 making it as 10 – 1 = 9, So in total we have taken 6 + 1 = 7
from 16 in 2-counters, making equation as 16 – 7 = 9 as shown in the picture.

Question 4.
11 – 4 = ?
11 – ____1___ = 10
10 – ___3____ = ___7_____
So, 11 – 4 = ___7_____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-13

Answer:
11 – 1 = 10
10 – 3 = 7
So 11 – 4 = 7

Explanation:
To solve 11 -4  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 1 circles so in total we have 11,
Now in all we will strike 4 circles, 1 circles from counter-2 making equation
as 11 – 1 = 10 we got 10 in counter-1 and we strike 3 circles from counter-1
we are left with 9 making it as 10 – 3 = 7, So in total we have taken 1 + 3 = 4
from 11 in 2-counters, making equation as 11 – 4 = 7 as shown in the picture.

Question 5.
13 – 5 = ?
13 – ____3_____ = 10
10 – ____2_____ = ____8______
So, 13 – 5 = ____8____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-14
13 – 3 = 10
10 – 2 = 8
So 13 – 5 = 8

Explanation:
To solve 13 -5  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 3 circles so in total we have 13,
Now in all we will strike 5 circles, 3 circles from counter-2 making equation
as 13 – 3 = 10 we got 10 in counter-1 and we strike 3 circles from counter-1
we are left with 8 making it as 10 – 2 = 8, So in total we have taken 3 + 2 = 5
from 13 in 2-counters, making equation as 13 – 5 = 8 as shown in the picture.

Question 6.
MP Number Sense
Which equations did Newton use to solve the problem?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 46
Answer:
Newton uses Equation 3 : 12 – 2 =10 , 10 – 4 = 6 so we get 12 – 6 = 6

Explanation:
If we see picture we have two counters in total we have total 12 circles,
In counter-2 we have 2 strike out means 12 – 2 = 10 and from counter-1
we have 4 strike out so 10 – 4 = 6 so in total out of 12 we strike 6 making
the equation as 12 – 6 = 6.
Out of three equations Newton uses equation 12 – 2 = 10 , 10 – 4 = 6,
other equations have 17 count in total and only 3rd equation is having
12 count as per the given picture, So newton use Equation 3.

Think and Grow: Modeling Real Life

Your friend checks out 13 books. You check out 4 fewer. How many books do you check out?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 47
Model:
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 48
Subtraction equation:

____9___ books
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-15
I have checked 9 books.

Explanation:
Given my friend checks out 13 books and I check out 4 fewer,
Means I will take 2 counters in counter-1 I will have 10 books and counter-2
3 books in total 13 books, now I have 4 fewer means I will strike out 4,
3 from counter-2 and 1 from counter-1 in total 4 from both the counters,
So 13 – 4 = 9, I checked 9 books.

Show and Grow

Question 7.
Your friend skips 16 stones. You skip 8 fewer. How many stones do you skip?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 49
Model:
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 50
Subtraction equation:

_____8_______ stones
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-16
16 – 8 = 8
So I skip 8 stones.

Explanation:
Given my friend skips 16 stones and I skip 8 fewer,
Means I will take 2 counters in counter-1 I will have 10 stones and counter-2
6 stones in total 16 stones, now I have 8 fewer means I will strike out 8 ,
6 from counter-2 and 2 from counter-1 in total 8 from both the counters,
So 16 – 8 = 8, I skip 8 stones.

Get to 10 to Subtract Practice 5.4

Get to 10 to Subtract

Question 1.
15 – 6 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 51
15 – __5_____ = 10
10 – ___1____ = __9______
So, 15 – 6 = ____9____ .
Answer:
15 – 5 = 10
10 -1 = 9
So, 15 – 6 = 9.

Explanation:
To solve 15 -6  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 5 circles so in total we have 15,
Now in all we will strike 6 circles, 5 circles from counter-2 making equation
as 15 – 5 = 10 we got 10 in counter-1 and we strike 1 circle from counter-1
we are left with 9 making it as 10 – 1 = 9, So in total we have taken 5 + 1 = 6
from 15 in 2-counters, making equation as 15 – 6 = 9 as shown in the picture.

Question 2.
12 – 4 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 52
12 – ___2____ = 10
10 – ___2____ = ___8_____
So, 12 – 4 = ___8_____ .
Answer:
12 – 2 = 10
10 -2 = 8
So, 12 – 4 = 8.

Explanation:
To solve 12 -4  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 2 circles so in total we have 12,
Now in all we will strike 4 circles, 2 circles from counter-2 making equation
as 12 – 2 = 10 we got 10 in counter-1 and we strike 2 circles from counter-1
we are left with 8 making it as 10 – 2 = 8, So in total we have taken 2 + 2 = 4
from 12 in 2-counters, making equation as 12 – 4 = 8 as shown in the picture.

Question 3.
13 – 7 = ?
13 – ___3____ = 10
10 – ___4____ = ___6_____
So, 13 – 7 = ____6____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-17
13 – 3 = 10
10 – 4 = 6
13 – 7 = 6

Explanation:
To solve 13 -7  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 3 circles so in total we have 13,
Now in all we will strike 7 circles, 3 circles from counter-2 making equation
as 13 – 3 = 10 we got 10 in counter-1 and we strike 4 circles from counter-1
we are left with 6 making it as 10 – 4 = 6, So in total we have taken 3 + 4 = 7
from 13 in 2-counters, making equation as 13 – 7 = 6 as shown in the picture.

Question 4.
14 – 8 = ?
14 – ___4____ = 10
10 – ___4____ = ___6_____
So, 14 – 8 = ____6____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-18
14 – 4 = 10
10 – 4 = 6
14 – 8 = 6

Explanation:
To solve 14 -8  and to get 10,
We solve by using 2 counters in counter one we have 10 circles
and in next counter two we have 4 circles so in total we have 14,
Now in all we will strike 8 circles, 4 circles from counter-2 making equation
as 14 – 4 = 10 we got 10 in counter-1 and we strike 4 circles from counter-1
we are left with 6 making it as 10 – 4 = 6, So in total we have taken 4 + 4 = 8
from 14 in 2-counters, making equation as 14 – 8 = 6 as shown in the picture.

Question 5.
MP Number Sense
Which equations did Descartes use to solve the problem?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 53
Answer:

Descartes uses Equation 1 : 15 – 5 =10 , 10 – 4 = 6 so we get 15 – 9 = 6

Explanation:
If we see picture we have two counters in total we have total 15 circles,
In counter-2 we have 5 strike out means 15 – 5 = 10 and from counter-1
we have 4 strike out so 10 – 4 = 6 so in total out of 15 we strike 9 making
the equation as 15 – 9 = 6.
Out of three equations Newton uses equation 15 – 5 = 10 , 10 – 4 = 6,
other equations have 20 count in total and only 1st equation is having
15 count as per the given picture, So newton use 1 Equation.

Question 6.
Modeling Real Life
Your friend recycles 14 cans. You recycle 7 fewer. How many cans do you recycle?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 54
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 55

____7_____ cans
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-19

I recycle 7 cans.

Explanation:
Given my friend recycle 14 cans and I recycle 7 fewer,
Means I will take 2 counters in counter-1 I will have 10 cans and counter-2
4 cans in total 14 cans, now I have 7 fewer means I will strike out 7,
4 from the counter-2 and 3 from counter-1 in total 7 from both the counters,
So 14 – 7 = 7, I recycle 7 cans.

Review & Refresh

Is the equation true or false?

Question 7.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 56
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-20
3 + 2 = 5 + 0
5 = 5 ,
So True.

Explanation:
We take 3 + 2 means adding 3 and 2 we get 3 + 2 = 5
and 5 + 0 is 5 so both sides are equal therefore
3 + 2 = 5 + 0 is True.

Question 8.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 57
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-21
8 – 2 = 6 ≠ 5 + 5 = 10
6 ≠ 10
So False

Explanation:
We take 8 – 2 means subtracting 2 from 8 we get 8 – 2 = 6
and 5 + 5 means adding 5 and 5 we get 5 + 5  =10,
If we see both sides they are not equal as 6 ≠ 10,
So 8 – 2 = 5 + 5 is False.

Lesson 5.5 More True or False Equations

Explore and Grow

Color the stars that have a sum or difference equal to 19 – 5.

Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 58
Answer:
https://ccssmathanswers.com/wp-content/uploads/2021/01/Big-Ideas-Math-Answers-Grade-1-Chapter-5-Subtract-Numbers-within-20-22.bmp
Explanation:
We color the stars that have a sum or difference equal to 19 – 5,
means  19 – 5 = 14, We check each star if equal to 14 we will color.
a. The sum is 9 + 5 = 14, so color it with green,
b. The difference is 20 – 6 = 14, we color it with blue
c. The sum is 12 + 1 + 1 = 14, we color it with green
d. The difference is 16 – 2 = 14, we color it with blue
e. The difference is 13 – 1 = 12 , we will not color it
as this is not equal to 14.
f. The sum is 14 + 0 = 14 , we will color it with green

Show and Grow

Is the equation true or false ?

Question 1.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 59
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-23
As 17 – 9 = 8  ≠ 14 -5 = 9
So False

Explanation:
We take 17 – 9 means subtracting 9 from 17 we get 17 – 9 = 8
and 14 – 5 means subtracting 5 from 14 we get 14 – 5 = 9,
If we see both sides they are not equal as 8 ≠ 9,
So 17 – 9 = 14 – 5 is False.

Question 2.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 60
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-24
As 6 + 5 = 11 = 18 – 7 = 11
So True.

Explanation:
We take 6 + 5 means adding 6 and 5 we get 6 + 5 = 11,
and 18 – 7 means subtracting 7 from 18 we get 18 – 7 = 11,
As both sides are equal therefore
6 + 5 = 11 = 18 – 7 = 11 is True

Apply and Grow: Practice

Is the equation true or false?

Question 3.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 61
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-25

As 5 + 7 = 12  ≠  3 + 8 = 11
So False

Explanation:
We take 5 + 7 means adding 5 and 7 we get 5 + 7 = 12,
and 3 + 8 means adding 3 and 8 we get 3 + 8 = 11,
As both sides are not equal therefore
5 + 7 = 12 ≠ 3 + 8 = 11 is False.

Question 4.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 62
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-26
As 4 + 9 = 13 = 5 + 3 + 5 = 13
Is True.

Explanation:
We take 4 + 9 means adding 4 and 9 we get 4 + 9 = 13,
and 5 + 3 + 5  means adding 5 , 3 and 5 we get 5 + 3 + 5 = 13,
As both sides are equal therefore
4 + 9 = 13 = 5 + 3 + 5 = 13 is True.

Question 5.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 63
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-27

As 12 – 7 = 5 ≠ 13 – 5 = 8
So False.

Explanation:
We take 12 – 7 means subtracting 7 from 12 we get 12 – 7 = 5,
and 13 – 5 means subtracting 5 from 13 we get 13 – 5 = 8,
As both sides are not equal therefore
12 – 7  = 5 ≠ 13 – 5 = 8 is False.

Question 6.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 66
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-28

As 14 – 8 = 6 = 12 – 6 = 6
So True.

Explanation:
We take 14 – 8 means subtracting 8 from 14 we get 14 – 8 = 6,
and 12 – 6 means subtracting 6 from 12 we get 12 – 6 = 6,
As both sides are equal therefore
14 – 8  = 6 = 12 – 6 = 6 is True.

Question 7.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 64
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-29
1 + 8 = 9 = 16 -7 = 9
So True.

Explanation:
We take 1 + 8  means adding 1 and 8 we get 1 + 8  = 9,
and 16 – 7 means subtracting 7 from 16 we get 16 – 7 = 9,
As both sides are equal therefore
1 + 8  = 9 = 16 – 7 = 9 is True.

Question 8.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 65
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-30
18 – 9 = 9 ≠  5 + 1 + 4 = 10
So False.

Explanation:
We take 18 – 9  means subtracting 9 from 18 we get 18 – 9  = 9,
and 5 + 1 + 4 means adding 5,1 and 4 we get 5 + 1 + 4 = 10,
As both sides are not equal therefore
18 – 9  = 9 ≠ 5 + 1 + 4 = 10 is False.

Question 9.
MP Number Sense
Circle all of the equations that are true.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 67
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-31

Explanation:
Given equations are a. 20 = 2 as 20 is not equal to 2,false so we will not circle,
b. 19 – 7 = 12 as 19 – 7 is 12 this is true we will circle it.
c. 6 + 6 + 3 = 7 + 8 as 6 + 6 + 3 = 15 and 7 + 8 = 15, Both are same
and true we will circle the equation.

Think and Grow: Modeling Real Life

You hove 12 lemons. You use 4 of them. Your friend has 3 lemons and buys 4 more.
Do you each have the same number of lemons?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 68
Equation:
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 69
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-32
No each do not have the same number of lemons as 8 ≠ 7 .

Explanation:
Given I have 12 lemons and use 4 of them means 12 – 4
My friend have 3 lemons and buys 4 more means 3 + 4
now checking both of them 12 – 4 = 8 and 3 + 4 = 7 as 8 ≠ 7
both are not equal each do not have the same number of lemons.

Show and Grow

Question 10.
You have 14 grapes. You eat 7 of them. Your friend has 10 grapes and eats 3 of them.
Do you each have the same number of grapes?
Equation:
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 70
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-34
Yes each have the same number of grapes as 7 = 7.

Explanation:
Given I have 14 grapes and I eat 7 of them means 14 -7
My friend has 10 grapes and eats 3 of them means 10 – 3,
Now checking both we have 14 – 7 = 7 and 10 – 3 = 7,
Both are equal, So, Yes each of them have the same number of grapes 7= 7.

More True or False Equations Practice 5.5

Is the equation true or false?

Question 1.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 71
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-35
13 – 9 = 4 = 11 – 7 = 4
So True.

Explanation:
Checking 13 – 9 and 11 – 7 , subtracting 9 from 13 we get 4
and subtracting 7 from 11 we get 4
as both equations values are equal, true.

Question 2.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 72
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-36
9 + 8 = 17 = 17 + 0 = 17
So True.

Explanation:
Checking 9 + 8 and 17 + 0, as 9 + 8 = 17 and
17 + 0 = 17 as both equations values are equal to 17 so true.

Question 3.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 73
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-37
12 – 4 = 8 ≠ 15 – 6 = 9,
So False.

Explanation:
Checking 12 – 4 and 15 – 6, We get 12 – 4 = 8 and
15 – 6 = 9 as both equations values are not equal 8 ≠ 9,
So false.

Question 4.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 74
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-38
4 + 5 = 9 ≠ 11 – 3 = 8
Is False

Explanation:
Checking 4 + 5 and 11 – 3, We get 4 + 5 = 9 and
11 – 3 = 8 as both equations values are not equal 9 ≠ 8,
So false.

Question 5.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 75
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-39
15 – 7 = 8 = 4 + 4 = 8
So True.

Explanation:
Checking 15 – 7 and  4 + 4  we get 15 – 7 = 8
and  4 + 4 = 8 as both equations values are same 8 = 8
so true.

Question 6.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 76
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-40
0 + 5 + 2 = 7 = 12 – 5 =  7
So True.

Explanation:
Checking 0 + 5 + 2 = 12 – 5, We get 0 + 5 + 2 = 7
and 12 – 5 = 7 as both equations values are same 7 = 7
so true.

Question 7.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 77
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-41
16 – 8 = 8  ≠  2 + 3 + 2 = 7
So False

Explanation:
Checking 16 – 8 and 2 + 3 + 2 we see 16 – 8 = 8
and  2 + 3 + 2 = 7 as both equations are not equal
8 ≠ 7 so false.

Question 8.
MP Number Sense
Circle all of the equations that are false.
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 78
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-42
Explanation:
Checking equations
a. 7 + 2 = 9 and 11 -2 = 9 both are equal so true we will not circle.
b. 3 , 12 – 8 = 4 as 3 ≠  4, So false we will circle it.
c. 4 + 1 + 4 = 9 and 14 -6 = 12 as 9 ≠ 12 , So false we will circle it.

Question 9.
Modeling Real Life
You have 9 badges. You earn 3 more. Your friend has 5 badges and earns 7 more. Do you each have the same number of badges?
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 79
Big Ideas Math Answer Key Grade 1 Chapter 5 Subtract Numbers within 20 80
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-43
Yes , each have the same number of badges.

Explanation:
Given I have 9 badges and  earn 3 more means 9 + 3 = 12,
My friend has 5 badges and earns 7 more means 5 + 7 = 12,
as both are having 12 badges Yes, I and my friend each
have same number of badges .

Review & Refresh

Question 10.
_____4____ + 2 = 6
Answer:
4 + 2 = 6

Explanation:
Given _______ + 2 = 6, Let us take missing number as X,
X + 2 = 6 means X = 6 – 2 = 4, X = 4 So missing number is 4,
the equation is 4 + 2 = 6.

Question 11.
____6____ + 3 = 9
Answer:
6 + 3 = 9

Explanation:
Given _______ + 3 = 9, Let us take missing number as X,
X + 3 = 9 means X = 9 – 3 = 6, X = 6 So missing number is 6,
the equation is 6 + 3 = 9.

Lesson 5.6 Make True Equations

Explore and Grow

Complete the equation.

14 – 5 = 3 + __________

Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 81
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-44
14 – 5 = 3 + 6

Explanation:
Given 14 – 5 = 3 + ________ Let us take missing number as X,
First we see 14 – 5 on number line we move
5 steps left from 14 we get 9, means 3 + X = 9
so to get X we move on number line from 3 till 9
we got 6 units means X = 6,
therefore the true equation is 14 – 5 = 3 + 6.

Show and Grow

Question 1.
? + 6 = 10 – 3
? + 6 = __7______
___1_____ + 6 = ___7____

So, ____1____ + 6 = 10 – 3.
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-45
1 + 6 = 10 – 3

Explanation:
Given _____ + 6 = 10 – 3
Now first we start from 10 and move 3 units back on the
number line we get 7, 10 – 3 = 7 now from 6 we will move
right till we get 7 we moved 1 unit means 6 + 1  = 7,
So the true equation is 1 + 6 = 10 – 3.

Question 2.
12 – 9 = ? – 5
____3____ = ? – 5
____3____ = __8_____ – 5

So, 12 – 9 = ____8____ – 5.
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-46
12 – 9 = 8 – 5

Explanation:
First we find 12 – 9 we start from 12 on number line
and move 9 units back we get 3 means 12 – 9 = 3 and ____ – 5 = 3,
Let us take missing number as X and X – 5 = 3 , therefore X = 3 + 5
on number line we move 3 units right from 5 we get 8,
making the true equation as 12 – 9 = 8 – 5.

Apply and Grow: Practice

Question 3.
? + 8 = 9 + 6
? + 8 = __15______
____7____ + 8 = _15___

So, ___7_____ + 8 = 9 + 6.
Answer:
_ + 8 = 9 + 6
_ + 8 = 15
7 + 8 = 15
So 7 + 8 = 9 + 6

Explanation :

Given ___ +  8 = 9 + 6, First we see 9 + 6 = 15 means
____ + 8 = 15 So let us take missing number as X ,
X + 8 = 15 therefore X = 15 – 8 = 7 making true equation as
7 + 8 = 9 + 6.

Question 4.
13 – 8 = ? – 6
___5_____ = ? – 6
____5____ = __11_ – 6

So, 13 – 8 = __11_ – 6.
Answer:
13 – 8 = _______ – 6
5 = ______ – 6
5 = 11 – 6
So 13 – 8 = 11 – 6

Explanation:
Given 13 – 8 = ____ – 6 means first we see 13 – 8 we get 5
means _____ – 6 = 5 let us take missing number as X
So X – 6 = 5, X = 5 + 6 = 11 making the true equation as
13 – 8  = 11 – 6.

Question 5.
14 – 6 = ? + 2
___8_____ = ? + 2
____8____ = ___6____ + 2

So, 14 – 6 = ____6____ + 2.
Answer:
14 – 6 = _____ + 2
8 = ________ + 2
8 = 6 + 2
So 14 – 6 = 6 + 2

Explanation:
Given 14 – 6 is equal to ________ + 2 , first we see 14 – 6 we get
8 means _______ + 2 = 8 , let us take missing number as X
so 8 = X + 2 means X = 8 – 2 = 6 making the true equation as
14 – 6 = 6 + 2.

Question 6.
15 – ? = 3 + 3
15 – ? = __6______
15 – ___9_____ = ___6____

So, 15 – ____9____ = 3 + 3.
Answer:
15 – ___ = 3 + 3
15 – ___ =  6
15 – 9 = 6
15 – 9 = 3 + 3

Explanation:
Given 15 – ___ = 3 + 3 means first we see 3 + 3 = 6,
means 15 – __ = 6 , Let us take X as missing number means
15 – X = 6 we get X = 15 – 6 = 9  therefore 15- 9 = 6,
making true equation as 15 – 9 = 3 + 3.

Question 7.
_____12_____ – 6 = 3 + 2 + 1
Answer:
12 – 6 = 3 + 2 + 1

Explanation:
Given __________ – 6 = 3 + 2 + 1 we see first
3 + 2 + 1 = 6 means ________ – 6 = 6,
let us take missing number as X , X – 6 = 6,
X = 6 + 6 = 12 making the true equation as 12 – 6 = 3 + 2 + 1.

Question 8.
6 + 4 + 4 = 6 + _______
Answer:
6 + 4 + 4 = 6 + 8

Explanation:
Given 6 + 4 + 4 = 6 + _______, First we add 6 + 4 + 4 we get 14
means 14 = 6 + ____, we will take missing number as X So that
6 + X = 14 , X = 14 – 6 = 8 making the true equation as 6 + 4 + 4 = 6 + 8.

Question 9.
YOU BE THE TEACHER
Newton says 2 makes the equation true. Is Newton correct? Show how you know.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 82
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-47
Yes, Newton is correct, as 7 + 2 = 9 = 11 – 2.

Explanation:
Given the equation as 7 + 2 = 11 -____ and newton says 2
makes the equation true, First we see 7 + 2 = 9
on number line we move 2 steps from 7 we get 9 so
now on number line we need to reach 9  from 11
so we will move 2 steps back or left we reach 9 so 11 – 2 = 9,
Both equations are equal so Newton is true.

Think and Grow: Modeling Real Life

You catch 11 butterflies. 4 fly away. Your friend catches 3 butterflies.
How many more butterflies must your friend catch to have the same number as you?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 83
Equation:
___11____ – ___4_____ = ____3___ + ?

____4______ butterflies

11 – 4  = 3 + 4
My friend should catch 4 butterflies to have same number as me.

Explanation :
Given I catch 11 butterflies. 4 fly away means I have
11 – 4 = 7 butterflies now and my friend catches 3 butterflies
to have same number of butterflies let my friend should catch
X butterflies as 3 + X = 7 so X = 7 – 3 = 4 making equation as
11 – 4 = 3 + 4. Therefore my friend should catch 4 butterflies
to have same number as me.

Show and Grow

Question 10.
You catch 15 leaves. 6 of them blow away. Your friend catches 12 leaves and some of them blow away. Now you each have the same number of leaves. How many of your friend’s leaves blow away?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 84
Equation:
___15____ – ___6_____ = ___12____ – ?

______3____ leaves
15 – 6 = 12 – 3,
3 leaves of my friend’s blow away.

Explanation:
Given I catch 15 leaves and 6 of them blow away means I have
15 – 6 = 9, Your friend catches 12 leaves and some of them blow away
lets take it as X number and given I & my friend have same number of leaves now
12 – X = 9 , X = 12 – 9 = 3. So 3 leaves of my friend’s blow away.

Make True Equations Practice 5.6

Question 1.
12 – ? = 8 – 4
12 – ? = __4______
12 – ___8_____ = ___4____

So, 12 – ___4_____ = 8 – 4.
Answer:
12 – ____ = 8 – 4
12 – ___ = 4
12 – 8 = 4
So, 12 – 8 =  8 – 4

Explanation:
Given equation as 12 – ___ = 8 – 4, first we see 8 – 4
we get as 4, 8-4 = 4 So 12 – ___ = 4,
Let us take missing number as X so 12 – X = 4,
X = 12 – 4= 8, Now the true equation is 12 – 8 = 8 – 4.

Question 2.
7 + 9 = 8 + ?
____16____ = 8 + ?
_____16___ = 8 + ___8____

So, 7 + 9 = 8 + ___8_____ .
7 + 9 = 8 + ___
16 = 8 + ___
16 = 8 + 8
So, 7 + 9 = 8 + 8

Explanation:
Given equation as 7 + 9 = 8 + __,  So first we see
7 + 9 = 16 means 8 + ___ = 16 ,Let us take X as missing number
8 + X = 16, X = 16 – 8  = 8, Now the true equation is 7 + 9 = 8 + 8

Question 3.
4 + 3 = __________ – 7
Answer:
4 + 3 = 14 – 7

Explanation:
Given 4 + 3 = ___ – 7, first we see 4 + 3 we get 7,
means 7  = ____ – 7, Let us take X as missing number
so 7 = X – 7, X = 7 + 7 = 14 making true equation as
4 + 3 = 14 – 7.

Question 4.
7 + _________ = 17 – 0
Answer:
7 + 10 = 17 – 0

Explanation:
Given as 7 + ___ = 17 – 0 first we see 17 – 0 we get 17
means 7 + ___ = 17, Now we take missing number as X,
7 + X = 17, X = 17 – 7 = 10 therefore the true equation is
7 + 10 = 17 – 0.

Question 5.
__________ + 20 = 8 + 10 + 2
Answer:
0 + 20 = 8 + 10 + 2

Explanation:
Given ____ + 20 = 8 + 10 + 2, We solve first 8 + 10 + 2
we get 20 so  ____ + 20 = 20, Let us take missing number as X,
X + 20 = 20 therefore X = 20 -20 = 0 , Making true equation as
0 + 20 = 8 + 10 + 2.

Question 6.
3 + 1 + 1 = 14 – __________
Answer:
3 + 1 + 1 = 14 – 9

Explanation:

Given 3 + 1 + 1 = 14 – ____, first we see 3 + 1 + 1 we get
5 and 14 – ___ = 5 , Let us take missing number as X, 14 – X = 5,
X = 14 – 5 = 9, making true equation as 3 + 1 + 1 = 14 – 9.

Question 7.
YOU BE THE TEACHER
Descartes says 5 makes the equation true. Is Descartes correct? Show how you know.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 85
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-48
17 – 9 ≠ 5 – 2 ,So Descartes is in correct.

Explanation:
Given equation is 17 – 9 = ___ – 2 and 5 makes the equation true ,
we see first 17 – 9 on number line we start from 17 and move 9 units back
we get 8 means 17 – 9 = 8, Now we take as per Descartes 5 – 2 on number line
we start from 5 and move 2 units back we get 3 which is not equal to 8,
So 17 – 9 ≠ 5 – 2 ,So Descartes is in correct.

Question 8.
Modeling Real Life
You catch 14 fireflies. You lose 8 of them. Your friend catches 11 fireflies and loses some of them.
Now you each have the same number of fireflies. How many fireflies does your friend lose?
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 86
___14_____ – ___8____ = ___11____ – ?

__5_____ fireflies
14 – 8 = 11 – 5, My friend loses 5 fireflies.

Explanation:
Given I catch 14 fireflies and lose 8 of them, means I have
14 – 8 = 6 with me, My friend catches 11 fireflies and
loses some of them let us take my friend loses X fireflies and
each have the same number of fireflies means 11 – X = 6, So
X = 11 – 6 = 5, making the equation as 14 – 8 = 11 – 5,
therefore my friend loses 5 fireflies.

Review & Refresh

Question 9.
color the rectangles.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 87
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-49

Explanation:
Given in the picture we have four shapes and we color the third shape
which is rectangle means a quadrilateral with four right angles, or a parallelogram
containing a right angle, so colored it with purple color.

Question 10.
color the squares.
Big Ideas Math Answers 1st Grade 1 Chapter 5 Subtract Numbers within 20 88
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-50
Explanation:
Given in the picture we have four shapes and we color the first shape
which is rectangle means a quadrilateral with four right angles, or a parallelogram
containing a right angle, so colored it with orange color.

Lesson 5.7 Problem Solving: Subtraction within 20

Explore and Grow

Model the story.

There are 18 seagulls. Some of them fly away. There are 9 left. How many seagulls flew away?

_____9___ seagulls
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-51
18 – 9 = 9
9 seagulls flew away.

Explanation:
Given there are 18 seagulls. Some of them fly away.
There are 9 left means out of 18 we are left with 9,
Let us take X number of them fly away means
18 – X  = 9, X = 18 – 9 = 9, We show in bar model as
total we have 18, 9 left and 9 seagulls flew away.

show and Grow

Question 1.
You have some stuffed animals. You give 3 away. You have 8 left. How many stuffed animals did you have to start?
Circle what you know.
Underline what you need to find.
Solve:
____11____ ○ ___3______ = ____8______

_____11_____ stuffed animals
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-52
11 – 3 = 8
I have to start with 11 stuffed animals.

Explanation:
Given I have some stuffed animals and I give 3 away so have 8 left,
let I have X number of stuffed animals so From X  gave 3 so
X – 3 = 8 , X = 8 + 3 = 11 I know I gave 3 and left with 8 so I circled them,
I need to know how many stuffed animals I had so underlined it
as shown above in the picture. making equation as 11 – 3 = 8,
therefore I have to start with 11 stuffed animals.

Apply and Grow: Practice

Question 2.
A group of students are at an arcade. 8 of them leave. There are 3 left. How many students were at the arcade to start?
Circle what you know.
Underline what you need to find.
Solve:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 89
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-53
11 – 8 = 3,
11 students were at the arcade to start.

Explanation:
Given a group of students are at an arcade let us take as X,
8 of them leave and there are 3 left means X – 8 = 3,
X = 3 + 8 = 11 as shown in bar model  8 leave and 3 left total 11.
the equation is 11 – 8 = 3, I circled 8 and 3 I know, underlined 11
to find. So there are 11 students at the arcade to start.

Question 3.
You have 15 trucks. Your friend has 7. How many more trucks do you have?

_____8____ more trucks
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-54
15 – 7 = 8
I have 8 more trucks.

Explanation:
Given I have 15 trucks and friend have 7, So more trucks I have than my
friend are 15 – 7 = 8, as shown in bar model I have 15 and friend have
7 and 8 more trucks I have than my friend.

Question 4.
DIG DEEPER
You have 16 stickers. Your friend has 7 fewer than you. Which bar model shows how many stickers your friend has?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 90
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-55
16 – 7 = 9
circled the equation shown in bar model which
shows how many stickers my friend has.

Explanation:
Given I have 16 stickers and my friend has 7 fewer than me
means my friend have 16 – 7 = 9 stickers ,So I have circled the
equation shown in bar model which shows how many stickers my friend has.

Think and Grow: Modeling Real Life

Your friends mask has 13 feathers. Your mask has 7 feathers. How many fewer feathers does your mask have?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 91
Circle what you know.
Underline what you need to find.
Solve:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 92
_________ – ________ = _________ fewer feathers
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-56
Explanation:
Given friends mask has 13 feathers and my mask has 7 feathers,
So I have 13 – 7 = 6 feathers fewer in my mask as shown in the bar model
I have circled 13, 7 in the equation as I know how many my friend
and I have and underlined 6 so that how many fewer feathers my mask have.

Show and Grow

Question 5.
There are 12 party hats. There are 5 fewer noisemakers than party hats. How many noisemakers are there?
Circle what you know.
Underline what you need to find.
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 93
Solve:
____12_____ – ____5____ = ____7_____ noisemakers
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-57
12 – 5 = 7
So there are 7 noisemakers.

Explanation:
Given there are 12 party hats and there are 5 fewer
noisemakers than party hats means 12 – 5 = 7 noisemakers
are available, as I know how many party hats and how many fewer
noisemakers are there so I circled them 12, 5 and I need to find how
many noisemakers are there so I underlined 7 in the equation.

Problem Solving: Subtraction within 20 Practice 5.7

Question 1.
You have 12 erasers. Your friend takes some of them. You have 5 left. How many erasers does your friend take?
Circle what you know.
Underline what you need to find.
Solve:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 94
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-58
12 – 7 = 5
My friend have taken 7 erasers.

Explanation:
Given I have 12 erasers and my friend takes some of them
and I have 5 left. Let my friend takes X number so
12 – X = 5, X = 12 – 5 = 7 , So 12 – 7 = 5 as shown in bar model,
As I know 12 and 5 I have circled it and I need to find
how many my friend have taken so I have underlined 7 in the
equation.

Question 2.
You have 17 glitter pens. Your friend has 9 fewer than you. How many does your friend have?

_____8______ glitter pens
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-59
17 – 9 = 8,
My friend have 8 glitter pens.

Explanation:
Given I have 17 glitter pens and my friend has 9 fewer than me,
Now let us take my friend have X number of glitter pens so
X = 17 – 9, X = 8 therefore my friend have 8 glitter pens.

Question 3.
DIG DEEPER!
A group of students are at a library. 6 of them leave. There are 7 left. Which part-part whole model shows how many students were at the library to start?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 95
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 96
Answer:
Second One Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-60shows
13 number students were there at the library to start.

Explanation:
Given a group of students are at a library 6 of them leave and
there are 7 left. So a number of students were there at the library
to start are 6 + 7 = 13, so the second one part-part whole model shows
how many students were there at the library to start.

Question 4.
Modeling Real Life
Your friend’s shirt has 14 buttons. Your shirt has 7 fewer. How many buttons does your shirt have?
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 97
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 98

___________ buttons
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-61
14 – 7 = 7
My shirt have 7 buttons.

Explanation:
Given my friend’s shirt has 14 buttons and my shirt has 7 fewer,
So my shirt have 14 – 7 = 7 buttons as shown in the bar model
therefore my shirt has 7 buttons.

Review & Refresh

Question 5.
There are 8 Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 99.
3 Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 99 swim away.
How many Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 99 are left?
____8____ – ___3____ = ___5_____ Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20 99
Answer:
8 – 3 = 5,
There are 5 seals left.

Explanation:
Given there are 8 seals and 3 of them swim away means
from 8 we will take 3 making equation as 8 – 3 = 5,
So there are 5 seal left.

Chapter 5 Subtract Numbers within 20 Performance Task

Question 1.
You keep track of the number of honeybees and bumblebees you see.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 100

a. How many more honeybees did you see on Monday than on Tuesday?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 101

_____6_____ more honeybees
Answer:

12 – 6 = 6,
I have 6 more honeybees seen on Monday than on Tuesday.

Explanation:
Given track of the number of honeybees seen
in that on Monday it is 12 and on Tuesday it is 6,
more number of honeybees seen are 12 – 6 = 6 on Monday than on Tuesday.

b. How many fewer bees did you see on Monday than on Tuesday?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 101

_____9_____ fewer bees
Answer:
14 – 5 = 9
9 fewer bees I have seen on Monday than on Tuesday.

Explanation:
Given track of the number of bees  seen
in that on Monday it is 5 and on Tuesday it is 14, now on Monday
it is less than Tuesday  so out of 14 we have seen 5 means
we have 14 – 5  = 9  fewer bees seen on Monday than on Tuesday.

c. How many bumblebees must you see on Wednesday so that the numbers of bees you see on
Tuesday and Wednesday are the same?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 101

____14______ bumblebees
Answer:
14 number of bumblebees I must see on Wednesday so that the numbers
of bees I see on Tuesday and Wednesday are the same.

Explanation:
Given track of the number of bumblebees seen on Tuesday are 14, So
bumblebees I must  see on Wednesday so that the numbers of bees I see on
Tuesday and Wednesday are the same are 14 only as both days is should be the same.

Chapter 5 Subtract Numbers within 20 Chapter Practice

Count Back to Subtract within 20 Homework & Practice 5.1

Question 1.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
11 – 3 = ____8______
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-62

11 – 3 = 8

Explanation:
We subtract 11 – 3 = 9, on number line we start at 11 and
move 3 steps back or left we get 8.

Question 2.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
13 – 4 = _____9_____
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-63
13 – 4 = 9

Explanation:
We subtract 13 – 4 = 9, on number line we start at 13 and
move 4 steps back or left we get 9.

Question 3.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
____12______ = 15 – 3
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-64
12 = 15 – 3

Explanation:
We subtract 15 – 3 = 12, on number line we start at 15 and
move 3 steps back or left we get 12.

Question 4.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
____8______ = 16 – 8
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-65
8 = 16 – 8

Explanation:
We subtract 16 – 8 = 8, on number line we start at 16 and
move 8 steps back or left we get 8.

Use Addition to Subtract within 20 Homework & Practice 5.2

Question 5.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
11 – 9 = ?
Think 9 + ___2____ = 11
So, 11 – 9 = ____2_____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-66

9 + 2 = 11
11 – 9 = 2

Explanation:
First we move from 9 on number line and start moving till
11 we count how many units right we have moved we get
2 units, so 9 + 2 = 11 or we start at 11 on number line and
move 9 steps back or left we get 2, 11 – 9 = 2.

Question 6.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
13 – 8 = ?
Think 8 + __5_____ = 13
So, 13 – 8 = ____5_____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-67
8 + 5 = 13
13 – 8 = 5

Explanation:
First we move from 8 on number line and start moving till
13 we count how many units right we have moved we get
5 units, so 8 + 5 = 13 or we start at 13 on number line and
move 8 steps back or left we get 5 so 13 – 8 = 5.

Question 7.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
____13_____ = 20 – 7
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-68
13 + 7 = 20
20 – 7 = 13

Explanation:
First we move from 13 on number line and start moving till
20 we count how many units right we have moved we get
7 units, so 13 + 7 = 20 or we start at 20 on number line and
move 7 steps back or left we get 13 so 20 – 7 = 13.

Question 8.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 102
____9____ = 12 – 3
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-69
9 + 3 = 12
9 = 12 – 3

Explanation:
First we move from 9 on number line and start moving till
12 we count how many units right we have moved we get
3 units so 9 + 3 = 12 or we start at 12 on number line and
move 3 steps back or left we get 9 so 12 – 3 = 9.

Subtract 9 Homework & Practice 5.3

Get to 10 to subtract

Question 9.
15 – 9 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 103
15 – ____5____ = 10
10 – _____4_____ = ____6_____
So, 15 – 9 = ___6_____
Answer:
15 – 5 = 10
10 – 4 = 6
So, 15 – 9 = 6

Explanation:
We have 2 counters in counter one we have 10 circles
and in the next counter we have 5 circles so in total we have 15,
First we see out of 15 if we consider counter-2 we have 5 strike outs
means 15 – 5 = 10 we got 10 in counter-1 and if we see first counter
we have 4 strike outs 10 – 4 = 6, So total number of circles strike out
from 2-counters are 5 + 4 = 9, So making equation as 15 – 9 = 6.

Question 10.
17 – 9 =?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 104
17 – ___7_____ = 10
10 – _____2_____ = ____8_____
So, 17 – 9 = ____8____
Answer:
17 – 7 = 10
10 – 2 = 8
So, 17 – 9 = 8

Explanation:
We have 2 counters in counter one we have 10 circles
and in next counter we have 7 circles so in total we have 17,
First we see out of 17 if we consider counter-2 we have 7 strike outs
means 17 – 7 = 10 we got 10 in counter-1 and if we see first counter
we have 2 strike outs 10 – 2 = 8, So total number of circles strike out
from 2-counters are 7 + 2 = 9, So making equation as 17 – 9 = 8.

Get to 10 to subtract Homework & Practice 5.4

Get to 10 to subtract

Question 11.
12 – 7 = ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 105
12 – ____2_____ = 10
10 – ____5______ = ____5_____
So, 12 – 7 = _____5_____ .
Answer:
12 – 2 = 10
10 – 5 = 5
So, 12 – 7 = 5.

Explanation:
We have 2 counters in counter one we have 10 circles
and in the next counter, we have 2 circles so in total we have 12,
First, we see out of 12 if we consider counter-2 we have 2 strike outs
means 12 – 2 = 10 we got 10 in counter-1 and if we see first counter
we have 5 strike outs 10 – 5 = 5, So the total number of circles strike out
from 2-counters are 5 + 2 = 7, So making equation as 12 – 7 = 5.

Question 12.
17 – 8 = ?
17 – ____7____ = 10
10 – ____1_____ = ___9_____
So, 17 – 8 = ___9____ .
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-70
17 – 7 = 10
10 – 1 = 9
So, 17 – 8 = 9

Explanation:
We have 2 counters in counter one we have 10 circles
and in the next counter, we have 7 circles so in total we have 17,
First, we see out of 17 if we consider counter-2 we have 7 strike outs
means 17 – 7 = 10 we got 10 in counter-1 and if we see the first counter
we have 1 strike outs 10 – 1 = 9, So the total number of circles strike out
from 2-counters are 7+ 1 = 8, So making equation as 17 – 8 = 9.

More True or False Equations Homework & Practice 5.5

Is the equation true or false?

Question 13.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 106
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-71

8 + 3 + 8  = 13 + 6
19 = 19 ,
So True.

Explanation:
We take 8 + 3 + 8 means adding 8 to 3 and
again adding 8 we get 8 + 3 + 8 = 19
Now 13 + 6 is 19 so both sides are equal therefore
8 + 3 +8 = 13 + 6 is True.

Question 14.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 107
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-72
16 – 8 = 6 + 2
8 = 8
So True.

Explanation:
We take 16 – 8 means subtracting 8 from 16
we get 16 – 8 = 8,
Now 6 + 2 is 8 so both sides are equal therefore
16 – 6  = 6 + 2  is True.

Question 15.
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 108
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-73

14 – 7 = 7 ≠ 12 – 9 = 3
7 ≠ 3
So False

Explanation:
We take 14 – 7 means subtracting 7 from 14 we get 14 – 7 = 7
and 12 -9 means subtracting  9 from 12 we get 12 – 9 = 3,
If we see both sides they are not equal as 7 ≠ 3,
So 14 – 7 = 12 -9 is False.

Make True Equations Homework & Practice 5.6

Question 16.
11 – 7 = 10 – ?
___4____ = 10 – ?
___4____ = 10 – ___6_____
So, 11 – 7 = 10 – ___6_____ .
Answer:

11 – 7 = 10 – ____
___4____ = 10 – ___
___4____ = 10 – ___6_____
So, 11 – 7 = 10 – ___6_____ .

Explanation :
Given 11 – 7 = 10 –  ___, First we see 11 – 7 = 4 means
10 – ___ = 4 So let us take missing number as X ,
10 – X = 4 therefore X = 10 – 4 = 6 making true equation as
11 – 7 = 10 – 6.

Question 17.
2 + 0 + 6 = ? – 5
____8____ = ? – 5
____8____ = ___13___ – 5
So, 2 + 0 + 6 = ____13____ – 5
Answer:
2 + 0 + 6 = ____ – 5
____8____ = ___ – 5
____8____ = ___13___ – 5
So, 2 + 0 + 6 = ____13____ – 5

Explanation :
Given 2 + 0 + 6 = ___- 5 , First we see 2 + 0 + 6 = 8 means
___ – 5 = 8 So let us take missing number as X ,
X – 5 = 8 therefore X = 8 + 5 = 13 making true equation as
2 + 0 + 6 = 13 – 5.

Problem Solving: Subtraction within 20 Homework & Practice 5.7

Question 18.
There are 13 people on a train. Some of them exit. There are 5 left. How many people exit the train?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 109
Circle what you know.
Underline what you need to find.
Solve:
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 110

_____13_____ ○- ____8______ = _____5______, ____8_____ people
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-74
13 – 8 = 5
8 people exit the train.

Explanation:
Given there are 13 people on a train, some of them exit and
there are 5 left. On number line we start at 13 and move 5 units
left or back so we reach at 8 means 8 people exit the train,
As we know 13 people are on the train and 5 left we circle
in the equation and we need to know how many exit the train,
so we underline 8 in the equation  13 – 8 =5 above.

Question 19.
A group of students are at a museum. 8 of them leave. There are 7 left. How many students were there to start ?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 111

_____15_______ Students
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-75
8 + 7 = 15 or 15 – 8 = 7
There were 15 students at the start.

Explanation:
Given a group of students are at a museum, 8 of them leave,
There are 7 left. We start from 8 and move 7 units rights we get 15,
8 + 7 = 15, So there are 15 students at the start.

Question 20.
You and a friend play basketball. Your friend scores 17 points. You score 8 fewer. How many points do you score?
Big Ideas Math Solutions Grade 1 Chapter 5 Subtract Numbers within 20 112

_____9_______ points
Answer:
Big Ideas Math Answers Grade 1 Chapter 5 Subtract Numbers within 20-76
17 – 8 = 9
I scored 9 points.

Explanation:
Given I and a friend play basketball my friend scores 17 points
and I score 8 fewer. On the number line, I start from 17 and move
8 steps left I reach at 9 means 17 – 8 = 9, so I scored 9 points.

Conclusion:

Students can find Big Ideas Math Solution Keys for all the chapters at one place. All the Concepts in the Big Ideas Math Answer are prepared by the subject experts. Resolve all your queries and assess your preparation standard using the Common Core Big Ideas Math Grade 1 Answer Key.

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