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## Big Ideas Math Book 1st Grade Answer Key Chapter 2 Fluency and Strategies within 10

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**Vocabulary**

**Lesson 1: Add 0**

**Lesson 2 Subtract 0 and Subtract All**

**Lesson 3: Add and Subtract 1**

**Lesson 4: Add Doubles from 1 to 5**

**Lesson 5: Use Doubles**

**Lesson 6: Add in Any Order**

**Lesson 7: Count on to Add**

**Lesson 8: Count Back to Subtract**

**Lesson 9: Use Addition to Subtract**

**Performance Task**

### Fluency and Strategies within 10 Vocabulary

**Organize It**

Review words:

addend

sum

difference

Use the review words to complete the graphic organizer.

Question 1.

Answer:

Explanation:

A number that is added to another number is known as an addend.

In this case, 3 and 4 are the addends.

Sum is the result of adding two numbers.

So, 3 + 4 = 7

7 is the result that means sum.

Question 2.

Answer:

**Define It**

Use your vocabulary cards to match.

Answer:

Explanation:

A number line can be defined as a straight line with numbers placed at equal intervals or segments along its length. A number line can be extended infinitely in any direction and is usually represented horizontally.

Count on is nothing the count that goes forward.

Count back is nothing but count that goes backward.

### Lesson 2.1 Add 0

**Explore and Grow**

Use linking cubes to model each story.

There are 6 ducks in the pond. 0 ducks join them. How many ducks are in the pond flow?

____ ducks

Answer:

Number of ducks in pond = 6

Number of ducks joined= 0

Total number of ducks= 6+0=6 Ducks

Answer:

Number of ducks in pond = 0

Number of ducks joined= 8

Total number of ducks= 0+8=8 ducks

**Show and Grow**

Use the picture to write an equation.

Question 1.

Answer:

4 + 0 = 4

Explanation:

By seeing the above picture we say that one of the addend is 4 and another addend is 0.

Now add both the numbers

4 + 0 = 4

Thus the result is 4.

Question 2.

Answer:

0 + 1=1

Explanation:

From the above figure we notice 0 and 1 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 1 = 1

Thus the result is 1.

Question 3.

Answer:

0 + 6 = 6

Explanation:

From the above figure we notice 0 and 6 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 6 = 6

Thus the result is 6

Question 4.

Answer:

8 + 0 = 8

Explanation:

From the above figure we notice 0 and 8 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

8 + 0 = 8

Thus the result is 8.

**Apply and Grow: Practice**

Use the picture to write an equation.

Question 5.

Answer:

7 + 0 = 7

Explanation:

From the above figure we notice 0 and 7 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

7 + 0= 7

Thus the result is 7.

Question 6.

Answer:

0 + 10 = 10

Explanation:

From the above figure we notice 0 and 10 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 10 = 10

Thus the result is 10.

Question 7.

9 + 0 = _____

Answer:

9 + 0 = 9

Explanation:

From the above figure we notice 0 and 9 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

9 + 0 = 9

Thus the result is 9.

Question 8.

0 + 8 = ______

Answer:

0 + 8 = 8

Explanation:

From the above figure we notice 0 and 8 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 8 = 8

Thus the result is 8.

**DIG DEEPER!
**Find each sum. Think: What do you notice?

Question 9.

3 + 0 = ______

0 + 3 = ______

Answer:

3 + 0 = 3

0 + 3 = 3

We notice that any number added with 0 will be the same number.

Question 10.

0 + 6 = ______

6 + 0 = ______

Answer:

0 + 6 = 6

6 + 0 = 6

We notice that any number added with 0 will be the same number.

Question 11.

MP Logic

There are 7 penguins in all. How many penguins are inside the igloo?

Answer:

Total Number of penguins = 7

Number of penguins outside = 7

Number of penguins inside = x

x + 7 = 7

x = 0

**Think and Grow: Modeling Real Life**

There are no students at a bus stop. Then 9 students arrive. How many students are at the bus stop now?

Model:

Addition equation:

_________ students

Answer:

0 + 9 = 9

Number of students at bus stop = 9 students

Explanation:

From the above figure we notice 0 and 9 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 9 = 9

Thus the result is 9.

**Show and Grow**

Question 12.

Your friend does not have any tokens. You give your friend 7 tokens. How many tokens does your friend have now?

Model:

Addition equation:

__________ tokens

Answer:

0 + 7 = 7

Number of tokens with my friend = 7 tokens

Explanation:

From the above figure we notice 0 and 7 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 7 = 7

Thus the result is 7.

### Add 0 Practice 2.1

Use the picture to write an equation.

Question 1.

________ + 0 = _________

Answer:

9 + 0 = 9

Explanation:

From the above figure we notice 0 and 9 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

9 + 0 = 9

Thus the result is 9.

Question 2.

________ + 0 = _________

Answer:

0 + 3 = 3

Explanation:

From the above figure we notice 0 and 3 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 3 = 3

Thus the result is 3

Question 3.

10 + 0 = ________

Answer:

10 + 0 = 10

Explanation:

From the above figure we notice 0 and 10 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

10 + 0 = 10

Thus the result is 10.

Question 4.

0 + 5 = _______

Answer:

0 + 5 = 5

Explanation:

From the above figure we notice 0 and 5 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 5 = 5

Thus the result is 5.

Question 5.

0 + 6 = _______

Answer:

0 + 6 = 6

Explanation:

From the above figure we notice 0 and 6 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 6 = 6

Thus the result is 6.

Question 6.

0 + 0 = _______

Answer:

0 + 0 =0

Explanation:

From the above figure we notice 0 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 0 = 0

Thus the result is 0.

Question 7.

**DIG DEEPER!**

Find each sum. Think: What do you notice?

7 + 0 = ______

0 + 7 = ______

Answer:

7 + 0 = 7

0 + 7 = 7

Explanation:

From the above figure we notice 0 and 1 are addends . Adding 0 to any number gives the sum as the number itself. If the order of the addends changes, the sum stays the same.Now add both the numbers

0 + 1 = 1

Thus the result is 1.

Question 8.

**MP Logic**

There are 8 students in all. How many students are inside the museum?

Answer:

Number of students = 8

Number of students out side the museum= 8

Number of students inside the museum= x

x + 8 = 8

x = 0

Number of students inside the museum = 0

Question 9.

**Modeling Real Life**

There are no seals on the shore. Then 10 seals swim to the shore. How many seals are on the shore now?

__________ seals

Answer:

0 + 10 = 10

Number of seals on the shore = 0 + 10 = 10 seals

Explanation:

From the above figure we notice 0 and 10 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

0 + 10 = 10

Thus the result is 10.

**Review & Refresh**

Write the number of goldfish.

Question 10.

Answer:

1

Explanation:

As per above figure we notice only 1 goldfishes in the aquarium.

Question 11.

Answer:

3

Explanation:

As per above figure we notice 3 goldfishes in the aquarium.

Question 12.

Answer:

0

Explanation:

As per above figure we notice no goldfish in the aquarium.

Question 13.

Answer:

2

Explanation:

As per above figure we notice 2 goldfishes in the aquarium.

### Lesson 2.2 Subtract 0 and Subtract All

**Explore and Grow**

Use linking cubes to model each story.

There are 5 beavers on the log. None of the beavers leave. How many beavers are left?

________ beavers

Answer:

Number of beavers = 5

Number of beavers leave= 0

Number of beavers Remaining = 5 – 0 = 5

There are 5 beavers on the log. All of the beavers leave. How many beavers are left?

_________ beavers

Answer:

Number of beavers = 5

Number of beavers left = 5

Number of beavers remaining =5 – 5 = 0

**Show and Grow**

Use the picture to write an equation.

Question 1.

_________ – 0 = ________

Answer:

2 – 0 = 2

Explanation:

From the above equation we notice 2 is minuend and 0 is subtrahend. Subtracting 0 from any number gives the number itself as the difference. Now subtract the 2 and 0

2 – 0 = 2

Thus the difference is 2

Question 2.

_________ – _________ = 0

Answer:

1 – 1 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 3.

_________ – 0 = _________

Answer:

4 – 0 = 4

Explanation:

From the above equation we notice 4 is minuend and 0 is subtrahend. Subtracting 0 from any number gives the number itself as the difference. Now subtract the 4 and 0

4 – 0 = 4

Thus the difference is 4

Question 4.

_________ – _________ = 0

Answer:

2 – 2 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

**Apply and Grow: Practice**

Use the picture to write an equation.

Question 5.

_________ – 0 = _________

Answer:

8 – 0 = 8

Explanation:

From the above equation we notice 8 is minuend and 0 is subtrahend. Subtracting 0 from any number gives the number itself as the difference. Now subtract the 2 and 0

8 – 0 = 8

Thus the difference is 8

Question 6.

_________ – _________ = 0

Answer:

8 – 8 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 7.

5 – 5 = _______

Answer:

5 – 5 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 8.

6 – 0 = ________

Answer:

6 – 0 = 6

Explanation:

From the above equation we notice 6 is minuend and 0 is subtrahend Subtracting 0 from any number gives the number itself as the difference. Now subtract the 6 and 0

6 – 0 = 6

Thus the difference is 6

Question 9.

9 – 0 = ________

Answer:

9 – 0 = 9

Explanation:

From the above equation we notice 9 is minuend and 0 is subtrahend Subtracting 0 from any number gives the number itself as the difference. Now subtract the 9 and 0

9 – 0 = 9

Thus the difference is 9

Question 10.

7 – 7 = ________

Answer:

7 – 7 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 11.

**MP Structure**

Complete the equation. Then use the words to complete the sentence.

Words:

difference

number

subtract

4 – ______ = 4

When you ______ 0 from a number, the ______ is that ______ .

Answer:

4 – 0 = 4

When you subtract 0 from a number, the number is that difference.

Think and Grow: Modeling Real Life

Your friend has 7 pennies. You have 7 fewer pennies than your friend. How many do you have?

Draw a picture:

Subtraction equation:

_________ pennies

Answer:

Number of pennies with my friend = 7

Number of pennies with me = x

x = 7 – 7 (7 fewer than my friend )

x = 0

Number of pennies with me = 0

**Show and Grow**

Question 12.

You have 6 pieces of chalk. You give all of your chalk to your friend. How many pieces do you have left?

Draw a picture:

Subtraction equation:

_________ pieces of chalk

Answer:

Number of chalks with me = 6

Number of chalks given to my friend = 6

Number of chalks remaining with me = 6 – 6 = 0

### Subtract 0 and Subtract All Practice 2.2

Use the picture to write an equation.

Question 1.

________ – 0 = ________

Answer:

5 – 0 = 5

Question 2.

________ – _______ = 0

Answer:

5 – 5 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 3.

3 – 3 = _______

Answer:

3 – 3 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 4.

1 – 0 = _________

Answer:

1 – 0 = 1

Question 5.

1 – 1= _________

Answer:

1 – 1= 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 6.

7 – 0 = _________

Answer:

7 – 0 = 7

Question 7.

**MP Structure**

Complete the equation. Then use the words to complete the sentence.

Words:

difference

number

subtract

9 – ______ = 0

When you ______ a ______ from itself, the ______________ is 0.

Answer:

9 – 9 = 0

When you subtract a number from itself, the difference is 0

Question 8.

Modeling Real Life You have 4 stuffed animals. You give all of them to your friend. How many stuffed animals do you have left?

________ stuffed animals

Answer:

Number of stuffed animals with me = 4

Number of stuffed animals given to my friend= 4

Number of stuffed animals remaining = 4 – 4 = 0

**Review & Refresh**

Write the number of dots you see on each domino. Then write the numbers in order.

Question 9.

Answer:

Question 10.

Answer:

### Lesson 2.3 Add and Subtract 1

**Explore and Grow**

Use linking cubes to model each story.

There are 7 kids on the bench. 1 kid joins them. How many kids are on the bench flow?

__________ kids

Answer:

Number of kids = 7

Number of kids joined = 1

Total number of kids = 7 + 1 = 8

There are 8 kids on the bench. 1 kid leaves. How many kids are left?

__________ kids

Answer:

Number of kids = 8

Number of kids left = 1

Total number of kids = 8 – 1 = 7

**Show and Grow**

Use the picture to write an equation.

Question 1.

___________ – __________ = ___________

Answer:

7 – 1 = 6

Explanation:

From the above figure, we notice six people are playing and one person is leaving . so we get equation as

6 + 1 = 7 .

In Total we notice 7 people in the picture .

Question 2.

___________ + __________ = ___________

Answer:

7 + 1 = 8

Explanation:

From the above figure, we notice 7 people are playing and 1 person is joining. so we get equation as

7 + 1 = 8 .

In Total we notice 8 people in the picture .

**Apply and Grow: Practice**

Use the picture to write an equation.

Question 3.

___________ + __________ = ___________

Answer:

9 + 1 = 10

Explanation:

From the above picture we notice 9 people in the pool and 1 person is joining the pool. so total number of people in pool is 9 + 1 = 10 .

Thus Total people in the pool are 10 people.

Question 4.

___________ + __________ = ___________

Answer:

8 + 1 = 9

Explanation:

From the above picture we notice 8 people in the pool and 1 person is leaving the pool. so total number of people in the picture is 8 + 1 = 9 .

Thus Total people are 9 people.

Question 5.

5 – 1 = ________

Answer:

5 – 1 = 4

Explanation:

From the above equation we notice 5 is minuend and 1 is subtrahend.

Now subtract

5 – 1 = 4

Thus the difference is 4

Question 6.

6 + 1 = ________

Answer:

6 + 1 = 7

Explanation:

From the above figure we notice 6 and 1 are addends .Now add both the numbers

6 + 1 = 7

Therefore the sum is 7.

Question 7.

8 + 1 = ________

Answer:

8 + 1 = 9

Explanation:

From the above figure we notice 8 and 1 are addends .Now add both the numbers

8 + 1 = 9

Therefore the sum is 9.

Question 8.

7 – 1 = ________

Answer:

7 – 1 = 6

Explanation:

From the above equation we notice 7 is minuend and 1 is subtrahend.

Now subtract

7 – 1 = 6

Thus the difference is 6

**DIG DEEPER!**

Circle the problem with the greater sum or difference.

Question 9.

2 – 1 2 + 1

Answer:

Explanation:

from above equations we get

2 – 1 = 1 as difference and

2 + 1 = 3 as sum

now compare difference and sum

1 < 3

Therefore , 3 is greater than 1

Question 10.

5 + 1 6 – 1

Answer:

Explanation:

from above equations we get

6 – 1 = 5 as difference and

5 + 1 = 6 as sum

now compare difference and sum

6 > 5

Therefore , 6 is greater than 5

Question 11.

**YOU BE THE TEACHER**

Circle to show who is correct. Show how you know?

Answer:

Explanation:

when a given number is increased by 1 then we get the next number of that number, Also, we know that a next number of a number is called successor.

From the number line we can notice when 3 is added with 1 we get 4 as sum which is next number of 3.

**Think and Grow: Modeling Real Life**

You have 9 action figures. Newton has 1 more than you. Descartes has 1 fewer than you. Who has more, Newton or Descartes?

Equations: Newton Descartes

Who has more Newton Descartes

Answer:

Number of action figures with me= 9

Number of action figures with Newton = 9 + 1 = 10

Number of action figures with Descartes = 9 – 1 = 8

Newton has 2 more action figures than Descartes.

**Show and Grow**

Question 12.

You have 5 video games. Newton has 1 fewer than you. Descartes has 1 more than you. Who has fewer, Newton or Descartes?

Equations: Newton Descartes

Who has fewer? Newton Descartes

Answer:

Number of video games with me = 5

Number of video games with Newton = 5 – 1 = 4

Number of video games with Descartes = 5 + 1 = 6

Newton has 2 fewer than Descartes.

### Add and Subtract 1 Practice 2.3

Use the picture to write an equation.

Question 1.

___________ + ___________ = ___________

Answer:

5 + 1 = 6

Explanation:

From the above equation we notice 5 and 1 are addends .when a given number is increased by 1 then we get the next number of that number as sum, next number of 5 is 6

Now add both the numbers

5 + 1 = 6

Therefore the sum is 6.

Question 2.

___________ – ___________ = ___________

Answer:

5 – 1 = 4

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 5 is 4 .

Therefore difference = 4

Question 3.

10 – 1 = ___________

Answer:

10 – 1 = 9

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 10 is 9 .

Therefore difference = 9

Question 4.

7 + 1 = ___________

Answer:

7 + 1 = 8

Explanation:

From the above Equation we notice 7 and 1 are addends .when a given number is increased by 1 then we get the next number of that number as sum, next number of 7 is 8

Now add both the numbers

7 + 1 = 8

Therefore the sum is 8.

**DIG DEEPER!**

Circle the problem with the greater sum or difference.

Question 5.

4 – 1 4 + 1

Answer:

Explanation:

from above equations we get

4 – 1 = 3 as difference and

4 + 1 = 5 as sum

now compare difference and sum

3 < 5

Therefore , 5 is greater than 3

Question 6.

7 + 1 8 + 1

Answer:

Explanation:

from above equations we get

7 + 1 = 8 as sum and

8 + 1 = 9 as sum

now compare both the sums

8 < 9

Therefore , 9 is greater than 8

Question 7.

**YOU BE THE TEACHER**

Circle to show who is correct. Show how you know.

Answer:

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 6 is 5 .

Therefore difference = 5

Question 8.

Modeling Real Life

You have 3 karate belts. Newton has I fewer than you. Descartes has I more than you. Who has fewer, Newton or Descartes?

Who has fewer? Newton Descartes

Answer:

Number of karate belts = 3

Number of belts with Newton = 3 – 1 = 2

Number of belts with Descartes = 3 + 1 = 4

Newton have 2 fewer belts than Descartes.

**Review & Refresh**

Question 9.

Use the picture to complete the number bond.

Answer:

### Lesson 2.4 Add Doubles from 1 to 5

**Explore and Grow**

Use counters to model the story.

You have 3 balls. Your friend has 3 balls. How many balls are there in all?

Answer:

Explanation:

Here we have 2 groups . each group contains 3 balls.

So total number of groups = 2

Total number of balls = 3 + 3 = 6

**Show and Grow**

Question 1.

___________ – ___________ = ___________

Answer:

4 – 4 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 2.

___________ + ___________ = ___________

Answer:

1 + 1 = 2

Explanation:

when a given number is increased by 1 then we get the next number of that number, Also, we know that a next number of a number is called successor.

The next number of 1 is 2.

Question 3.

Answer:

Explanation:

From the above figure we notice 4 are addends .Now add both the numbers

4 + 4 = 8

Therefore the sum is 8.

Question 4.

Answer:

Explanation:

From the above figure we notice 3 are addends .Now add both the numbers

3 + 3 = 6

Therefore the sum is 6.

**Apply and grow: Practice**

Question 5.

Answer:

Explanation:

From the above figure we notice 5 are addends .Now add both the numbers

5 + 5 = 10

Therefore the sum is 10.

Question 6.

Answer:

2 + 2 = 4

2 – 2 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 7.

2 + 2 = ______

Answer:

2 + 2 = 4

Explanation:

From the above figure we notice 2 are addends .Now add both the numbers

2 + 2 = 4

Therefore the sum is 4.

Question 8.

5 + 5 = _______

Answer:

5 + 5 = 10

Explanation:

From the above figure we notice 5 are addends .Now add both the numbers

5 + 5 = 10

Therefore the sum is 10.

Question 9.

Answer:

Explanation:

From the above figure we notice 3 are addends .Now add both the numbers

3 + 3 = 6

Therefore the sum is 6.

Question 10.

Answer:

Explanation:

From the above figure we notice 4 are addends .Now add both the numbers

4 + 4 = 8

Therefore the sum is 8.

Question 11.

**DIG DEEPER!**

Circle the equations you can complete using doubles.

________ + ________ = 6 ________ + ________ = 5

________ + ________ = 9 ________ + ________ = 2

Answer:

**Think and Grow: Modeling Real Life**

You and your friend color the same number of pictures. There are to pictures in all. How many pictures do you each color?

Draw a Picture:

Addition equation:

__________ pictures

Show and Grow

Question 12.

You and your friend have the same number of flowers. There are 8 flowers in all. How many flowers do you each have?

Draw a picture:

Addition equation:

________ flowers

Answer:

Number of flowers with me = x

Number of flowers with my friend = x

Total number of flowers = 8

x + x = 8

4 + 4 = 8.

### Add Doubles from 1 to 5 Practice 2.4

Question 1.

___________ + ___________ = ___________

Answer:

4 + 4 = 8

Question 2.

Answer:

Explanation:

From the above figure we notice 3 are addends .Now add both the numbers

3 + 3 = 6

Therefore the sum is 6.

Question 3.

2 + 2 = ________

Answer:

2 + 2 = 4

Explanation:

From the above figure we notice 2 are addends .Now add both the numbers

2 + 2 = 4

Therefore the sum is 4.

Question 4.

4 + 4 = _________

Answer:

4 + 4 = 8

Explanation:

From the above figure we notice 4 are addends .Now add both the numbers

4 + 4 = 8

Therefore the sum is 8.

Question 5.

Answer:

Explanation:

From the above figure we notice 5 are addends .Now add both the numbers

5 + 5 = 10

Therefore the sum is 10.

Question 6.

Answer:

Explanation:

From the above figure we notice 3 are addends .Now add both the numbers

3 + 3 = 6

Therefore the sum is 6.

Question 7.

**DIG DEEPER!**

Circle the equations you can complete using doubles.

_________ + _________ = 3 _________ + _________= 8

_________ + _________ = 4 _________ + _________ = 7

Answer:

Question 8.

**Modeling Real Life**

Newton and Descartes each have the same number of linking cubes. There are 6 linking cubes in all. How many linking cubes do Newton and Descartes have?

________ linking cubes

Answer:

Total Number of linking cubes = 6.

Newton and Descartes each have the same number of linking cubes

Each have 3 linking cubes

3 + 3 = 6.

Newton and Descartes each have 3 linking cubes.

**Review & Refresh**

Use the picture to write an equation.

Question 9.

___________ + ___________ = ___________

Answer:

2 + 3 = 5

Explanation:

we notice 2 hippos in the mud and 3 hippos came to join them.

so total number of hippos are add 2 and 3

Total number of hippos = 2 + 3 = 5

Question 10.

___________ + ___________ = ___________

Answer:

4 + 5 = 9

Explanation:

We notice 4 zebras eating grass and 5 zebras joining them

so total number of zebras are add 4 and 5

Total number of zebras = 4 + 5 = 9

### Lesson 2.5 Use Doubles

**Explore and Grow**

Use counters to model the story.

You collect 4 shells. Your friend collects 4 shells. How many shells are there in all?

____ shells

Answer:

Number of shells with me = 4

Number of shells with my friend= 4

Total Number of shells = 4 + 4 = 8

You collect 4 shells. Your friend collects 5 shells. How many shells are there in all?

____ shells

Answer:

Number of shells with me = 4

Number of shells with my friend= 5

Total Number of shells = 4 + 5 = 9

Show and Grow

Use the double 3 + 3 to find each sum.

Question 1.

3 + 4 = ______

Answer:

3 + 3 + 1 = 7

Answer:

3 + 3 – 1 = 5

**Apply and Grow: Practice**

Use the double 2 + 2 to find each sum.

Question 2.

2 + 3 = ______

Answer:

2 + 2 + 1 =5

2 + 1 = ______

Answer:

2 + 2 – 1 = 3

Find the sum. Write the double you used.

Question 3.

Answer:

3 + 4 = 7

3 + 3 + 1 = 6 + 1 = 7

Question 4.

Answer:

Question 5.

**MP Number Sense**

Use each card once to write two addition equations.

Answer:

2 + 2 = 4

2 + 3 = 5

**Think and Grow: Modeling Real Life**

You eat 4 grapes. Your friend eats I more than you. How many grapes do you and your friend eat in all?

Which doubles can you use to find the sum?

4 + 4 5 + 5 3 + 3

Addition equation:

__________ grapes

Answer:

Number of grapes ate by me = 4

Number of grapes ate by my friend = 4 + 1

Number of grapes eaten = 4 + 4 + 1 = 9

4 + 4 is used to find the sum

**Show and Grow**

Question 6.

You have 5 toy cars. Your friend has I fewer than you. How many cars do you and your friend have in all?

Which doubles can you use to find the sum?

4 + 4 6 + 6 5 + 5

Addition equation:

_________ toy cars

Answer:

Number of toy cars with me = 5

Number of toy cars with my friend = 5 – 1

Total Number of cars = 5 + 5 – 1 = 10 – 1 = 9

### Use Doubles Practice 2.5

Use the double 4 + 4 to find each sum.

Question 1.

4 + 5 = _______

Answer:

4 + 4 + 1 = 8 + 1 = 9

4 + 3 = _______

Answer:

4 + 4 – 1 = 8 – 1 = 7

Find the sum. Write the double you used.

Question 2.

Answer:

1 + 1 = 2

1 + 2 = 3

Question 3.

Answer:

1 + 1 = 2

3 + 2 = 5

Question 4.

**Number Sense**

Use each card once to write two addition equations.

Answer:

2 + 3 = 5

3 + 3 = 6

Question 5.

**Modeling Real Life**

Newton catches 2 butterflies. Descartes catches I more than Newton. How many butterflies do Newton and Descartes catch in all?

Which doubles can you use to find the sum?

3 + 3 1 + 1 2 + 2

_________ butterflies

Answer:

Number of butterflies with Newton = 2

Number of butterflies with Descartes = 2 + 1.

Total number of butterflies both caught = 2 + 2 + 1 = 4 + 1 = 5

**Review & Refresh**

Question 6.

Circle the model that shows the missing number.

2 + ______ = 5

Answer:

2 + 3 = 5

### Lesson 2.6 Add in Any Order

**Explore and Grow**

Use counters to model each problem. What do you notice?

4 + 3 = ____7_____

3 + 4 = ___7______

**Show and Grow**

Question 1.

_________ + _________ = _________

Answer:

2 + 4 = 6

Explanation:

From the above figure we notice 2 and 4 are addends .Now add both the numbers

2 + 4 = 6

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 6

_________ + _________ = _________

Answer:

4 + 2 = 6

Explanation:

From the above figure we notice 2 and 4 are addends .Now add both the numbers

2 + 4 = 6

Question 2.Whatever may be the order of addends the sum is always the same.

Therefore the sum is 6

_________ + _________ = _________

Answer:

7 + 1 = 8

Explanation:

when a given number is increased by 1 then we get the next number of that number as sum.

The next number of 7 is 8 as sum.

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 8

_________ + _________ = _________

Answer:

1 + 7 = 8

Explanation:

when a given number is increased by 1 then we get the next number of that number as sum.

The next number of 7 is 8 as sum.

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 8

Question 3.

Answer:

2 + 3 = 5

Explanation:

From the above figure we notice 2 and 3 are addends .Now add both the numbers

2 + 3 = 5

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 5

Answer:

Explanation:

From the above figure we notice 2 and 3 are addends .Now add both the numbers

3 + 2 = 5

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 5

**Apply and Grow: Practice**

Question 4.

_________ + _________ = _________

Answer:

7 + 3 = 10

Explanation:

From the above figure we notice 7 and 3 are addends .Now add both the numbers

7 + 3 = 10

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 10

_________ + _________ = _________

Answer:

3 + 7 = 10

Explanation:

From the above figure we notice 3 and 7 are addends .Now add both the numbers

3 + 7 = 10

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 10

Find the sum. Then change the order of the addends. Write the new addition problem.

Question 5.

Answer:

Explanation:

From the above figure we notice 1 and 4 are addends .Now add both the numbers

1 + 4 = 5 or 4 + 1 = 5

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 5

Question 6.

Answer:

Explanation:

From the above figure we notice 5 and 2 are addends .Now add both the numbers

5 + 2 = 7 or 2 + 5 = 7

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 7

Question 7.

Answer:

2 + 6 = 8

6 + 2 = 8

Explanation:

From the above figure we notice 6 and 2 are addends .Now add both the numbers

6 + 2 = 8 or 2 + 6 = 8

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 8

Question 8.

Answer:

9 = 8 + 1

9 = 1 + 8

Explanation:

From the above figure we notice 8 and 1 are addends .Now add both the numbers

8 + 1 = 9 or 1 + 8 = 9

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 9

Question 9.

**MP Number Sense**

Use the numbers shown to write two addition equations.

Answer:

4 + 5 = 9

5 + 4 = 9

Explanation:

From the above figure we notice 4 and 5 are addends .Now add both the numbers

4 + 5 = 9 or 5 + 4 = 9

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 9

**Think and Grow: Modeling Real Life**

You have 7 shirts. 3 are green. The rest are blue. How many blue shirts do you have?

Which equations describe your shirts?

3 + 4 = 7 3 + 7 = 10

7 + 3 = 10 4 + 3 = 7

Show how you know:

You have ____ blue shirts.

Answer:

Number of green shirts = 3

Number of blue shirts = X

Total number of shirts = 7

3 + X = 7

X = 7 – 3 = 4

Number of blue shirts = 4

Equation: 3 + 4 = 7 or 4 + 3 = 7

**Show and Grow**

Question 10.

You have 5 cups. 2 are yellow. The rest are red. How many red cups do you have?

Which equations describe your cups?

5 + 2 = 7 2 + 3 = 5

2 + 5 = 7 3 + 2 = 5

Show how you know:

You have ____ red cups.

Answer:

Number of red cups = x

Number of yellow cups = 2

Total number of cups = 5

x + 2 = 5

x = 5 – 2 = 3

Number of red cups = 3

Equation : 3 + 2 = 5 or 2 + 3 = 5

### Add in Any Order Practice 2.6

Question 1.

Answer:

Explanation:

From the above figure we notice 3 and 4 are addends .Now add both the numbers

3 + 4 = 7 or 4 + 3 = 7

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 7

Question 2.

Answer:

7 + 2 = 9

Answer:

2 + 7 = 9

Explanation:

From the above figure we notice 2 and 7 are addends .Now add both the numbers

2 + 7= 9 or 7 + 2 = 9

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 9

Find the sum. Then change the order of the addends. Write the new addition problem.

Question 3.

Answer:

Explanation:

From the above figure we notice 6 and 4 are addends .Now add both the numbers

6 + 4 = 10 or 4 + 6 = 10

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 10

Question 4.

Answer:

6 = 5 + 1

6 = 1 + 5

Explanation:

From the above figure we notice 6 and 4 are addends .Now add both the numbers

5 + 1 = 6 or 1 + 5 = 6

when a given number is increased by 1 then we get the next number of that number as sum

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 6

Question 5.

**MP Number Sense**

Use the numbers shown to write two addition equations.

Answer:

2 + 8 = 10

8 + 2 = 10

Explanation:

From the above equations we notice 2 and 8 are addends .Now add both the numbers

2 + 8 = 10 or 8 + 2 = 10

Whatever may be the order of addends the sum is always the same.

Therefore the sum is 10

Question 6.

**Modeling Real Life**

You have 7 tomatoes. 2 are red. The rest are yellow. How many yellow tomatoes do you have?

Which equations describe your tomatoes?

2 + 5 = 7 5 + 2 = 7

7 + 2 = 9 2 + 7 = 9

Show how you know:

You have _______ yellow tomatoes.

Answer:

Total number of tomatoes = 7

Number of red tomatoes = 2

Number of yellow tomatoes = x

Explanation:

7 = 2 + x

x = 7 – 2 = 5

Number of yellow tomatoes = 5

Equations: 2 + 5 = 7 or 5 + 2 = 7

**Review & Refresh**

Use the ten frame to complete the equation.

Question 7.

5 + _______ = 8

Answer:

5 + 3 = 8

Explanation:

From the above equation we notice to get 8 as sum what should be added for 5

if we add 3 to 5 we get 8 as sum.

Therefore 5 + 3 = 8 .

Question 8.

5 + ________ = 10

Answer:

5 + 5 = 10

Explanation:

From the above equation we notice to get 10 as sum what should be added for 5

if we add 5 to 5 we get 10 as sum.

Therefore 5 + 5 = 10 .

### Lesson 2.7 Count on to Add

**Explore and Grow**

Model the story.

There are 5 coins in a piggy bank. You put in 2 more. How many coins are in the bank now?

Answer:

Number of coins in piggy bank = 5

Number of coins added = 2

Total coins = 5 + 2 = 7.

**Show and Grow**

Question 1.

7 + 2 = _________

Answer:

7 + 2 = 9

Explanation:

Count on method to add numbers. To add 7 and 2, start from 7 and count on 2 steps to arrive at the sum (9).

Question 2.

3 + 1 = ________

Answer:

3 + 1 = 4

Explanation:

Count on method to add numbers. To add 3 and 1, start from 3 and count on 1 step to arrive at the sum (4).

Question 3.

4 + 6 = ________

Answer:

4 + 6 = 10

Explanation:

Count on method to add numbers. To add 4 and 6, start from 4 and count on 6 steps to arrive at the sum (10).

Question 4.

0 + 5 = ________

Answer:

0 + 5 = 5

Explanation:

Count on method to add numbers. To add 0 and 5, start from 0 and count on 5 steps to arrive at the sum (5).

**Apply and Grow: practice**

Question 5.

4 + 2 = _________

Answer:

4 + 2 = 6

Explanation:

Count on method to add numbers. To add 4 and 2, start from 4 and count on 2 steps to arrive at the sum (6).

Question 6.

6 + 1 = ________

Answer:

6 + 1 = 7

Explanation:

Count on method to add numbers. To add 6 and 1, start from 6 and count on 1 step to arrive at the sum (7).

Question 7.

Answer:

Explanation:

From the above figure we notice 5 and 4 are addends .Now add both the numbers

5 + 4 = 9

Therefore the sum is 9.

Question 8.

Answer:

Explanation:

From the above figure we notice 3 and 2 are addends .Now add both the numbers

3 + 2 = 5

Therefore the sum is 5.

Question 9.

________ = 0 + 7

Answer:

7 = 0 + 7

Explanation:

From the above figure we notice 0 and 7 are addends . Adding 0 to any number gives the sum as the number itself.Now add both the numbers

0 + 7 = 7

Thus the result is 7.

Question 10.

________ = 2 + 8

Answer:

10 = 2 + 8

Explanation:

From the above figure we notice 8 and 2 are addends .Now add both the numbers

2 + 8 = 10

Therefore the sum is 10.

Question 11.

**DIG DEEPER!**

Tell what problems Newton and Descartes solved. Think: How are the problems the same? How are they different?

Answer:

**Think and Grow: Modeling Real Life**

You and your friend are on a scavenger hunt. You find 3 clues. You and your friend find 8 clues in all. How many clues does your friend find?

Model:

______ clues

Answer:

Number of clues with me = 3

Number of clues with my friend = x

Total number of clues = 8

Explanation:

3 + x = 8

x = 8 – 3 = 5

Number of clues with my friend = 5

Equation: 3 + 5 = 8

Explanation:

Count on method to add numbers. To add 3 and 5 start from 3 and count on 5 steps to arrive at the sum (8).

**Show and Grow**

Question 12.

Your friend collects 4 cans. You and your friend collect 10 cans in all. How many cans do you collect?

Model:

________ cans

Answer:

Number of cans with my friend = 4

Total number of cans = 10

Number of cans with me = X

Explanation:

4 + X = 10

X= 10 – 4 = 6

Number of cans with me = 6

Equation: 4 + 6 = 10

Explanation:

Count on method to add numbers. To add 4 and 6, start from 4 and count on 6 steps to arrive at the sum (10).

### Count on to Add Practice 2.7

Question 1.

4 + 3 = ________

Answer:

4 + 3 = 7

Explanation:

Count on method to add numbers. To add 4 and 3 start from 3 and count on 3 steps to arrive at the sum (7).

Question 2.

8 + 1 = ________

Answer:

8 + 1 = 9

Explanation:

Count on method to add numbers. To add 8 and 1 start from 8 and count on 1 step to arrive at the sum (9).

Question 3.

6 + 2 = ________

Answer:

6 + 2 = 8

Explanation:

Count on method to add numbers. To add 6 and 2 start from 6 and count on 2 steps to arrive at the sum (8).

Question 4.

7 + 3 = ________

Answer:

7 + 3 = 10

Explanation:

Count on method to add numbers. To add 7 and 3 start from 7 and count on 3 steps to arrive at the sum (10).

Question 5.

Answer:

Explanation:

From the above figure we notice 0 and 9 are addends . Adding 0 to any number gives the sum as the number itself.Now add both the numbers

0 + 9 = 9

Thus the result is 9.

Question 6.

______ = 1 + 5

Answer:

6 = 1 + 5

Explanation:

when a given number is increased by 1 then we get the next number of that number as sum.

The next number of 5 is 6

Therefore sum = 6 .

Question 7.

**DIG DEEPER!**

Tell what problems Newton and Descartes solved. Think: How are the problems the same? How are they different?

Answer:

Both the problems are the same .

sum is the same only the order of the addends are different .

Newton have 3 and 4 as addends 3 added to 4 whereas in Descartes the 4 is added to 3. whatever may be the order of addends the sum will always be the same .

Question 8.

**Modeling Real Life**

You have 4 coins. You and your friend have 9 coins in all. How many coins does your friend have?

__________ coins

Answer:

Number of coins with me = 4

Number of coins with my friend = X

Total coins = 9

Explanation:

4 + X = 9

X = 9 -4 = 5

Number of coins with my friend = 5

Equation : 4 + 5 = 9

Explanation:

Count on method to add numbers. To add 4 and 5 start from 4 and count on 5 steps to arrive at the sum (9).

**Review & Refresh**

Use the picture to write an equation.

Question 9.

Answer:

4 – 1 = 3

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 4 is 3 .

Therefore difference = 3

Question 10.

Answer:

5 – 3 = 2

Explanation:

From the above equation we notice 5 is minuend and 3 is subtrahend.

Now subtract

5 – 3 = 2

Thus the difference is 2

### Lesson 2.8 Count Back to Subtract

**Explore and Grow**

Model the story.

There are 8 students in a line. 2 of them leave. How many students are left?

Answer:

Number of students = 8

Number of students left = 2

Number of students remained in class = 8 – 2 = 6

**Show and Grow**

Question 1.

5 – 4 = _________

Answer:

5 – 4 = 1

Explanation:

Use the count back method to subtract.To subtract 4 from 5, one can start at 5 and count back 4 steps we get difference as 1.

Question 2.

7 – 3 = ________

Answer:

7 – 3 = 4

Explanation:

Use the count back method to subtract.To subtract 3 from 7, one can start at 7 and count back 3 steps we get difference as 4.

Question 3.

6 – 1 = _________

Answer:

6 – 1 = 5

Explanation:

Use the count back method to subtract.To subtract 1 from 6, one can start at 6 and count back 1 step we get difference as 5.

Question 4.

10 – 8 = ________

Answer:

10 – 8 = 2

Explanation:

Use the count back method to subtract.To subtract 8 from 10, one can start at 10 and count back 8 steps we get difference as 2.

**Apply and Grow: Practice**

Question 5.

10 – 6 = _________

Answer:

10 – 6 = 4

Explanation:

Use the count back method to subtract.To subtract 6 from 10, one can start at 10 and count back 6 steps we get difference as 4.

Question 6.

9 – 3 = _________

Answer:

9 – 3 = 6

Explanation:

Use the count back method to subtract.To subtract 3 from 9, one can start at 9 and count back 3 steps we get difference as 6.

Question 7.

Answer:

Explanation:

From the above equation we notice 5 is minuend and 2 is subtrahends. Now subtract the 5 and 2

5 – 2 = 3

Thus the difference is 3

Question 8.

Answer:

Explanation:

From the above equation we notice 8 is minuend and 0 is subtrahends Subtracting 0 from any number gives the number itself as the difference. Now subtract the 8 and 0

8 – 0 = 8

Thus the difference is 8

Question 9.

________ = 7 – 6

Answer:

1

Question 10.

_________ = 4 – 1

Answer:

3

Question 11.

**MP Structure**

Write the problem shown.

_________ – _________ = ________

Answer:

9 – 5 = 4

Explanation:

Use the count back method to subtract.To subtract 5 from 9, one can start at 9 and count back 5 steps we get difference as 4.

**Think and Grow: Modeling Real Life**

There are 5 students on one side of a table and 5 students on the other. 7 students leave. How many students are left?

Model:

__________ students

Answer:

Total Number of students = 5 + 5 = 10

Number of students left = 7

Remaining Number of students = 10 – 7 = 3

Explanation:

Use the count back method to subtract.To subtract 7 from 10, one can start at 10 and count back 7 steps we get difference as 3

Show and Grow

Question 12.

You have 4 board games and 4 card games. You give 3 games to your friend. How many games do you have left?

Model:

__________ games

Answer:

Total Number of games = 4 + 4 = 8

Number of games given to my friend = 3

Remaining Number of games with me =8 – 3 = 5

Explanation:

Use the count back method to subtract.To subtract 3 from 8, one can start at 8 and count back 3 steps we get difference as 5

### Count Back to Subtract Practice 2.8

Question 1.

5 – 4 = ________

Answer:

5 – 4 = 1

Explanation:

Use the count back method to subtract.To subtract 4 from 5, one can start at 5 and count back 4 steps we get difference as 1

Question 2.

8 – 3 = ________

Answer:

8 – 3 = 5

Explanation:

Use the count back method to subtract.To subtract 3 from 8, one can start at 8 and count back 3 steps we get difference as 5

Question 3.

9 – 1 = ________

Answer:

9 – 1 = 8

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 9 is 8 .

Therefore difference = 8

Question 4.

6 – 2 = ________

Answer:

6 – 2 = 4

Explanation:

From the above equation we notice 6 is minuend and 2 is subtrahend.

Now subtract

6 – 2 = 4

Thus the difference is 4

Question 5.

Answer:

Explanation:

From the above equation we notice 7 is minuend and 5 is subtrahend.

Now subtract

7 – 5 = 2

Thus the difference is 2

Question 6.

__________ = 10 – 5

Answer:

5

Explanation:

From the above equation we notice 10 is minuend and 5 is subtrahend.

Now subtract

10 – 5 = 5

Thus the difference is 5

Question 7.

**MP Structure**

Write the problem shown.

__________ – _________ = _________

Answer:

9 – 7= 2

Explanation:

Use the count back method to subtract.To subtract 7 from 9, one can start at 9 and count back 7 steps we get difference as 2

Question 8.

Modeling Real Life

You have 4 star stickers and 4 heart stickers. You give 6 away. How many stickers do you have left?

__________ stickers

Answers:

Total Number of stickers = 4 + 4 = 8

Number of stickers given away = 6

Remaining number of stickers = 8 – 6 = 2

Explanation:

Use the count back method to subtract.To subtract 6 from 8, one can start at 8 and count back 6 steps we get difference as 2

**Review & Refresh**

Question 9.

Use the pictures to write the related equations.

Answer:

### Lesson 2.9 Use Addition to Subtract

**Explore and Grow**

Use counters to model each problem.

4 + ___3___ = 7

7 – 4 = __3___

**Show and Grow**

Question 1.

5 – 4 = ?

Think 4 + ______ = 5

So, 5 – 4 = _______ .

Answer:

Think 4 + 1 = 5

So, 5 – 4 = 1 .

Question 2.

6 – 3 = ?

Think 3 + ______ = 6

So, 6 – 3 = _______ .

Answer:

Think 3 + 3 = 6

So, 6 – 3 = 3 .

**Apply and Grow: Practice**

Question 3.

8 – 4 = ?

Think 4 + ______ = 8.

So, 8 – 4 = _______ .

Answer:

Think 4 + 4 = 8.

So, 8 – 4 = 4 .

Question 4.

7 – 5 = ?

Think 5 + ______ = 7.

So, 7 – 5 = _______ .

Answer:

Think 5 + 2 = 7.

So, 7 – 5 = 2 .

Question 5.

6 – 4 = ?

Think ______ + ______ = 6.

So, 6 – 4 = _______ .

Answer:

Think 2+ 4 = 6.

So, 6 – 4 = 2 .

Question 6.

9 – 6 = ?

Think ______ + ______ = 9.

So, 9 – 6 = _______ .

Answer:

Think 3 + 6 = 9.

So, 9 – 6 = 3 .

Question 7.

**YOU BE THE TEACHER**

There are 8 goats. 2 of them leave. Newton uses addition to tell how many goats are left. Is he correct? Show how you know.

Answer:

No, we have to subtract when goats leaves not addition.

8 – 2 = 6

**Think and Grow: Modeling Real life**

There are 10 puppies. 7 are brown. The rest are yellow. How many puppies are yellow?

Model:

Subtraction equation:

_________ puppies

Answer:

Total number of puppies = 10

Number of brown puppies = 3

Number of yellow puppies = 10 – 3 = 7

**Show and Grow**

Question 8.

There are 8 eggs. I of them hatches. How many eggs still need to hatch?

Model:

Subtraction equation:

__________ eggs

Answer:

Total number of eggs = 8

Number of eggs hatched = 1.

Numbers of eggs left for hatching = 8 – 1 = 7

### Use Addition to Subtract Practice 2.9

Question 1.

3 – 2 = ?

Think 2 + ______ = 3.

So, 3 – 2 = _______ .

Answer:

Think 2 + 1 = 3.

So, 3 – 2 = 1

Question 2.

10 – 5 = ?

Think 5 + ______ = 10.

So, 10 – 5 = _______ .

Answer:

Think 5 + 5 = 10.

So, 10 – 5 = 5

Question 3.

9 – 5 = ?

Think ______ + ______ = ______.

So, 9 – 5 = _______ .

Answer:

Think 4 + 5 = 9.

So, 9 – 5 = 4

Question 4.

7 – 6 = ?

Think ______ + ______ = ______.

So, 7 – 6 = _______ .

Answer:

Think 1 + 6 = 7.

So, 7 – 6 = 1

Question 5.

**YOU BE THE TEACHER**

There are 8 birds. 5 fly away. Descartes uses addition to tell how many birds are left. Is he correct? Show how you know.

Answer:

Numbers of birds = 8

Number of birds flew = 5

Remaining number of birds = 8 – 5 = 3

Descartes is wrong we need to subtract not addition .

Question 6.

Modeling Real Life There are 9 kittens. 7 are adopted. How many kittens still need to be adopted?

_______ kittens

Answer:

Total Number of kittens = 9

Number of kittens adopted = 7

Number of kittens remaining for adoption = 9 – 7 = 2

**Review & Refresh**

Question 7.

You have 5 and 2 How many dice do you have in all?

_________ + _________ = ________ dice

Answer:

5 + 2 = 7

Number of red dices = 5

Number of blue dices = 2

Total dices = 5 + 2 = 7

### Fluency and Strategies within 10 Performance Task

Question 1.

You plant 4 red flower seeds and 4 yellow flower seeds. Your friend plants 5 red flower seeds and 4 yellow flower seeds.

a. I of your yellow seeds does not grow. How many of your flowers grow?

_________ flowers

Answer:

Total number flower seeds = 4 + 4 = 8

Number of yellow seeds didn’t grow = 1

Number of your flowers grown = 8 – 1 = 7

b. 3 of your friend’s red seeds do not grow. How many of your friend’s flowers grow?

________ flowers

Answer:

Total number of my friends flowers = 5 + 4 = 9 (red and yellow )

Number of red seeds didn’t grow of my friend’s = 3

Number of your flowers grown of my friend’s= 9 – 3 = 6

c. Who has more flowers?

You Friend

Answer: I have more flowers

d. How many more red flowers do you have than your friend?

_______ flowers

Answer:

I have 4 red flowers

My friend 2 red flowers (5 – 3 )

### Fluency and Strategies within 10 Chapter Practice

### Add 0 Homework & Practice 2.1

Use the picture to write an equation.

Question 1.

_______ + 0 = ________

Answer:

2 + 0 = 2

Explanation:

From the above figure we notice 2 and 0 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

2 + 0 = 0

Thus the result is 2.

Question 2.

0 + _______ = ________

Answer:

0 + 5 = 5

Explanation:

From the above figure we notice 5 and 0 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

5 + 0 = 0

Thus the result is 5.

Question 3.

7 + 0 = ________

Answer:

7 + 0 = 7

Explanation:

From the above figure we notice 7 and 0 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

7 + 0 = 0

Thus the result is 7.

Question 4.

0 + 6 = ________

Answer:

0 + 6 = 6

Explanation:

From the above figure we notice 6 and 0 are addends . Adding 0 to any number gives the sum as the number itself. Now add both the numbers

6 + 0 = 0

Thus the result is 6.

### Subtract 0 and Subtract All Homework & Practice 2.2

Use the picture to write an equation.

Question 5.

________ – 0 = ________

Answer:

7 – 0 = 7

Explanation:

From the above equation we notice 7 is minuend and 0 is subtrahends Subtracting 0 from any number gives the number itself as the difference. Now subtract the 7 and 0

7 – 0 = 7

Thus the difference is 7

Question 6.

_________ – ________ = 0

Answer:

7 – 7 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 7.

9 – 9 = ______

Answer:

9 – 9 = 0

Explanation:

When a number is subtracted from itself the difference is always equal to 0.

Thus the difference is 0

Question 8.

8 – 0 = _______

Answer:

8 – 0 = 8

Explanation:

From the above equation we notice 8 is minuend and 0 is subtrahends Subtracting 0 from any number gives the number itself as the difference. Now subtract the 8 and 0

8 – 0 = 8

Thus the difference is 8

### Add and Subtract I Homework & Practice 2.3

Use the picture to write an equation.

Question 9.

________ + ________ = _________

Answer:

8 + 1 = 9

Explanation:

As per the above picture , we can notice 8 people are playing and 1 more person joining them

So total number of people are 8 + 1 = 9

Total number of people = 9

Question 10.

________ – ________ = _________

Answer:

8 – 1 = 7

Explanation:

As per the above picture , we can notice 7 people are playing and 1 person leaving them

So total number of people are 7 – 1 = 6

Total number of people = 6

Question 11.

3 – 1 = ________

Answer:

3 – 1 = 2

Explanation:

when a number is reduced by 1, then we get the previous number of that number as difference.

previous number of 3 is 2 .

Therefore difference = 2

Question 12.

5 + 1 = ________

Answer:

5 + 1 = 6

Explanation:

when a given number is increased by 1 then we get the next number of that number as sum

Therefore the sum is 6

### Add Doubles from 1 to 5 Homework & Practice 2.4

Question 13.

Answer:

2 + 2 = 4

Question 14.

Answer:

8 + 1 = 9

Question 15.

MP Reasoning

Circle the equations you can complete using doubles.

_________ + ________ = 10 _________ + ________ = 3

_________ + ________ = 6 _________ + ________ = 7

Answer:

### Use Doubles Homework & Practice 2.5

Use the doubles 2 + 2 to find each sum.

Question 16.

2 + 3 = _______

Answer:

2 + 3 = 5

2 + 2 + 1 = 5

2 + 1 = _______

Answer:

2 + 1 =3

2 + 2 – 1 = 3

Find the sum. Write the double you used.

Question 17.

Answer:

4 + 5 = 9

5 + 4 = 9

Question 18.

Answer:

### Add in any Order Homework & Practice 2.6

Question 19.

_______ + ______ = ______

Answer:

5 + 2 = 7

_______ + ______ = ______

Answer:

2 + 5 = 7

Question 20.

MP Number Sense

Use the numbers shown to write two addition equations.

Answer:

3 + 6 = 9

6 + 3 = 9

### Count on to Add Homework & Practice 2.7

Question 21.

5 + 2 = _________

Answer:

5 + 2 = 7

Explanation:

Count on method to add numbers. To add 5 and 2, start from 5 and count on 2 steps to arrive at the sum (7).

Question 22.

6 + 4 = __________

Answer:

6 + 4 = 10

Explanation:

Count on method to add numbers. To add 6 and 4, start from 6 and count on 4 steps to arrive at the sum (10).

### Count Back to Subtract Homework & Practice 2.8

Question 23.

9 – 7 = __________

Answer:

9 – 7 = 2

Explanation:

Use the count back method to subtract.To subtract 7 from 9, one can start at 9 and count back 7 steps we get difference as 2

Question 24.

10 – 5 = _________

Answer:

10 – 5 = 5

Explanation:

Use the count back method to subtract.To subtract 10 from 5, one can start at 10 and count back 5 steps we get difference as 5

### Use Addition to Subtract Homework & Practice 2.9

Question 25.

5 – 3 = ?

Think 3 + ______ = 5.

So, 5 – 3 = ______.

Answer:

Think 3 + 2 = 5.

So, 5 – 3 = 2

Question 26.

9 – 8 =?

Think 8 + ______ = 9.

So, 9 – 8 = ______.

Answer:

Think 8 + 1 = 9.

So, 9 – 8 = 1

*Conclusion:*

Follow Big Ideas Math Grade 1 Answers for the strong foundation. Move with every step of solving the process to solve your problems easily. Get the pdfs of all Big Ideas Math Grade 1 Chapters @bigideasmathanswer.com