All the solutions provided in **McGraw Hill Math Grade 3 Answer Key PDF Chapter 8 Lesson 4 Multiply by 8** will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 3 Answer Key Chapter 8 Lesson 4 Multiply by 8

**Math in My World**

Example 1

There are 6 trees along a street. In each tree, there are 8 birds. How many birds are there altogether?

Find 6 × 8.

Each tree has a group of 8 birds.

One Way Draw an array.

Another way Draw a picture.

Use an X for each bird.

There are ____ birds altogether.

Check

The Commutative Property shows that 6 × 8 has the same product as 8 × 6. Since 8 × 6 = ___, then 6 × 8 = ____.

The 4s facts are helpful in remembering the 8s facts.

Answer:

Given that,

There are 6 trees along a street.

In each tree there are 8 birds.

Each tree has a group of 8 birds.

The array of 6 x 8 is

The picture is

The Commutative Property shows that 6 × 8 has the same product as 8 × 6.

Since 8 × 6 = 48, then 6 × 8 = 48.

Example 2

Pearl counted 5 honeybees on each of 8 flowers. How many honeybees are there altogether? Write a number sentence with a symbol for the unknown.

Find 5 × 8 = .

Decompose 8 into equal addends of 4 + 4.

So, 5 × 8 = ____

The unknown is ____

There are ___ honeybees.

Answer:

Given that,

Pearl counted 5 honeybees on each of 8 flowers.

The total number of honeybees are

So, 5 × 8 = 40.

The unknown is 40.

There are 40 honeybees.

Talk Math

There are 4 groups of 8 students and 8 groups of 8 students, how many students are there altogether? Explain.

Answer:

Given that,

4 groups of 8 students means 4 x 8 = 32.

There are 32 students in 4 groups.

8 groups of 8 students means 8 x 8 = 64.

There are 64 students in 8 groups.

The total number of students all together is 32 + 64 = 96.

**Guided Practice**

**Complete the steps to find 7 × 8.**

Question 1.

Label the array.

Answer:

Multiplication of 7 with 8 then you get 56.

Convert 8 into 4 + 4.

7 x 4 = 28.

7 x 4 = 28.

28 + 28 = 56.

Question 2.

Double a known fact.

So, 7 × 8 = ____

Answer:

Multiplication of 7 with 4 then you get 28.

The product is 28.

Double the product is 28 + 28 = 56.

So, 7 x 8 = 56.

**Independent Practice**

**Double a known fact to find each product.**

Question 3.

3 × 8 = ____

3 × ___ = ____

3 × ____ = ____

___ + ____ = ____

Answer:

Multiplication of 3 with 8 then you get 24.

3 x 8 = 24.

convert 8 into 4 + 4.

3 x 4 = 12.

3 x 4 = 12.

Therefore 12 + 12 = 24.

Question 4.

10 × 8 = ____

Answer:

Multiplication of 10 with 8 then you get 80.

10 x 8 = 80.

Convert 8 into 4 + 4.

10 x 4 = 40.

10 x 4 = 40.

Therefore 40 + 40 = 80.

Question 5.

8 × 8 = ____

Answer:

Multiplication of 8 with 8 then you get 64.

8 x 8 = 64.

Convert 8 into 4 + 4.

8 x 4 = 32.

8 x 4 = 32.

Therefore 32 + 32 = 64.

Question 6.

9 × 8 = ___

Answer:

Multiplication of 9 with 8 then you get 72.

9 x 8 = 72.

Convert 8 into 4 + 4

9 x 4 = 36.

9 x 4 = 36.

Therefore 36 + 36 = 72.

**Use the Commutative Property to find each product. Write a related multiplication fact.**

Question 7.

1 × 8 = ___

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 1 with 8 then you get 8.

1 x 8 = 8.

Multiplication of 8 with 1 then you get 8.

8 x 1 = 8.

Question 8.

0 × 8 = ____

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 0 with 8 then you get 0.

0 x 8 = 0.

Multiplication of 8 with 0 then you get 0.

8 x 0 = 0.

Question 9.

6 × 8 = ____

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 6 with 8 then you get 48.

6 x 8 = 48.

Multiplication of 8 with 6 then you get 48.

8 x 6 = 48.

Question 10.

7 × 8 = ___

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 7 with 8 then you get 56.

7 x 8 = 56.

Multiplication of 8 with 7 then you get 56.

8 x 7 = 56.

Question 11.

2 × 8 = ___

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 2 with 8 then you get 16.

2 x 8 = 16.

Multiplication of 8 with 2 then you get 16.

8 x 2 = 16.

Question 12.

4 × 8 = ___

Answer:

Commutative property states that if change in order of the numbers in multiplication the product does not change.

Multiplication of 4 with 8 then you get 32.

4 x 8 = 32.

Multiplication of 8 with 4 then you get 32.

8 x 4 = 32.

**Algebra Find each unknown factor. Use the Commutative Property.**

Question 13.

8 × = 64

× 8 = 64

The unknown is ____.

Answer:

Multiplication of 8 with 8 then you get 64.

8 x 8 = 64.

8 x 8 = 64.

The unknown is 8.

Question 14.

× 1 = 8

1 × = 8

The unknown is ____.

Answer:

Multiplication of 8 with 1 then you get 8.

8 x 1 = 8.

1 x 8 = 8.

The unknown is 8.

Question 15.

8 × = 72

× 8 = 72

The unknown is ____.

Answer:

Multiplication of 8 with 9 then you get 72.

8 x 9 = 72.

9 x 8 = 72.

The unknown is 9.

**Multiply.**

Question 16.

Answer:

Multiplication of 0 with 8 then you get 0.

0 x 8 = 0.

Question 17.

Answer:

Multiplication of 8 with 3 then you get 24.

8 x 3 = 24.

Question 18.

Answer:

Multiplication of 5 with 8 then you get 40.

5 x 8 = 40.

Question 19.

Answer:

Multiplication of 6 with 8 then you get 48.

6 x 8 = 48.

**Problem Solving**

**Mathematical PRACTICE 1 Make a Plan Use the following information to solve Exercises 20-22.**

Mrs. Miller’s class of 8 students want to have one or more classroom pets.

Question 20.

If each student brought in 3 goldfish, how many goldfish would they have in the classroom?

Answer:

Given that,

The total number of students in the class room is 8.

The total number of goldfish brought by students are 3.

So, 8 x 3 = 24.

Therefore there are 24 goldfish in the classroom.

Question 21.

If each student brought in 2 hamsters, how many hamsters would they have in the classroom?

Answer:

Given that,

The total number of students in the class room is 8.

The total number of hamsters brought by the students are 2.

So, 8 x 2 = 16.

Therefore there are 16 hamsters in the classroom.

Question 22.

A pet store charges $10 for a lizard. If each student pays $5, how many lizards would they be able to purchase?

Answer:

Given that,

The total number of students in the class room is 8.

The pet store charges for a lizard is $10.

The each student pays $5.

The 8 students collect is 8 x $5 = 40.

So, The number of lizards are 40/10 = 4.

Therefore the number of lizards purchase by students are 4.

**HOT Problems**

Question 23.

**Mathematical PRACTICE 2 Use Number Sense** The row that represents the products of 8 from the multiplication table is shown below. Describe one pattern in the products of 8. Will this pattern continue? Explain.

Answer:

One patten is multiplies of 8 having 8, 6, 4, 2, 0 in the ones place and all the products of of the 8 are even. This this patten will continue.

Question 24.

**? Building on the Essential Question** When would I choose to decompose a multiplication fact rather than draw a picture?

Answer:

Decompose the multiplication fact is decompose the one of the factor to double the unknown fact.

Example is

4 x 6 = 24.

Decompose 6 into 3 + 3.

4 x 3 = 12.

4 x 3 = 12.

The picture is

### McGraw Hill My Math Grade 3 Chapter 8 Lesson 4 My Homework Answer Key

**Practice**

**Double a known fact to find each product.**

Question 1.

5 × 8 = ____

5 × ___ = ___

5 × ___ = ___

____ + ____ = ____

Answer:

Multiplication of 5 with 8 then you get 40.

5 x 8 = 40.

Convert 8 with 4 + 4.

5 x 4 = 20.

5 x 4 = 20.

The known fact is 20.

Double the product is 20 + 20 = 40.

Question 2.

4 × 8 = ____

4 × ___ = ___

4 × ___ = ___

____ + ____ = ____

Answer:

Multiplication of 4 with 8 then you get 32.

4 x 8 = 32.

Convert 8 into 4 + 4.

4 x 4 = 16.

4 x 4 = 16.

The known fact is 16.

Double the product is 16 + 16 = 32.

**Algebra Find each unknown. Use the Commutative Property.**

Question 3.

8 × = 40

× 8 = 40

The unknown is ___.

Answer:

Multiplication of 8 with 5 then you get 40.

8 x 5 = 40.

5 x 8 = 40.

The unknown is 5.

Question 4.

× 8 = 56

8 × = 56

The unknown is ___.

Answer:

Multiplication of 7 with 8 then you get 56.

7 x 8 = 56.

8 x 7 = 56.

The unknown is 7.

Question 5.

2 × 8 =

8 × 2 =

The unknown is ___.

Answer:

Multiplication of 2 with 8 then you get 16.

2 x 8 = 16.

Multiplication of 8 with 2 then you get 16.

8 x 2 = 16.

The unknown is 16.

Question 6.

8 × = 64

× 8 = 64

The unknown is ___.

Answer:

Multiplication of 8 with 8 then you get 64.

8 x 8 = 64.

8 x 8 = 64.

The unknown is 8.

**Multiply.**

Question 7.

Answer:

Multiplication of 1 with 8 then you get 8.

1 x 8 = 8.

Question 8.

Answer:

Multiplication of 8 with 9 then you get 72.

8 x 9 = 72.

Question 9.

Answer:

Multiplication of 8 with 0 then you get 0.

8 x 0 = 0.

Question 10.

Answer:

Multiplication of 3 with 8 then you get 24.

3 x 8 = 24.

**Problem Solving**

**Mathematical PRACTICE 2 Use Symbols Write a multiplication sentence with a symbol for the unknown. Then solve.**

Question 11.

There were 5 dolphins swimming around a tour boat. Each dolphin circled the boat 8 times. What is the total number of times all of the dolphins circled the boat?

Answer:

Given that,

There are 5 dolphins swimming around a tour boat.

Each dolphin circled the boat 8 times.

So, 5 x 8 = 40.

Therefore the total number of times all of the dolphins circled the boat is 40.

Question 12.

Cameron worked 8 hours at the coffee shop. He earned the same amount in tips each hour. At the end of his shift, Cameron had $32 in tips. How much money did he earn in tips each hour?

Answer:

Given that,

Cameron worked 8 hours at the coffee shop.

He earned the same amount in tips each hour.

Cameron had $32 in tips.

So, $32/8 = $4.

Therefore Cameron earn in tips for each hour is $4.

**Test Practice**

Question 13.

Stuart knows spiders have 8 legs. Which shows a known fact Stuart can double to find the number of legs on 7 spiders?

A. 4 × 3 = 12

B. 4 × 7 = 28

C. 4 × 8 = 32

D. 7 × 8 = 56

Answer:

Given that,

The total number of legs per each spider is 8 legs.

The total number of spiders are 7.

Therefore 8 x 7 = 56.

Option D is the correct answer.