All the solutions provided in **McGraw Hill My Math Grade 3 Answer Key PDF Chapter 7 Lesson 4 Multiply by 4 **will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 3 Answer Key Chapter 7 Lesson 4 Multiply by 4

**Math in My World**

**Example 1**

A box is packed with 4 rows of oranges. Each row has 9 oranges. How many oranges are in the box?

Find 4 × 9.

Decompose 4 into equal addends of 2 + 2.

Use the known fad of 2 × 9 and double it.

The array shows that 2 × 9 plus ____________ × 9 equals __________ × 9.

So, 4 × 9 = _____________. There are ______________ oranges in the box.

Answer:

Given that,

A box is packed with 4 rows of oranges.

Each row has 9 oranges.

The array shows that 2 × 9 plus 2 × 9 equals 4 × 9.

So, 4 × 9 = 36.

There are 36 oranges in the box.

**Example 2**

There are 3 bunches of bananas. Each bunch has 4 bananas. How many bananas are there altogether? Write a multiplication sentence with a symbol for the unknown. Then solve.

Solve by decomposing the factor 4 into two equal addends of 2.

Use the known fact 3 × 2 plus 3 × 2 to find the unknown.

So, 3 × 4 = ______________. The unknown is ______________.

There are ______________ bananas altogether.

Answer:

Given that,

There are 3 bunches of bananas.

Each bunch has 4 bananas.

So, 3 × 4 = 12.

The unknown is 12.

There are 12 bananas altogether.

**Talk Math**

Explain how knowing 2 × 7 can help you find 4 × 7.

Answer:

Given that,

2 x 7

Multiplication of 2 x 7 is 14.

2 x 7 = 14.

Product is the 14.

Double the product is 14 + 14 = 28.

Add 2x 7 + 2 x 7 then you get 4 x 7.

4 x 7 = 28.

Therefore 2 x 7 is helped to find the 4 x 7.

**Guided Practice**

Question 1.

Double a known fact to find 6 × 4. Label the array and complete the number sentences.

12 + 12 = ______________.

So, 6 × 4 = _______________.

Answer:

12 is the product.

Double the product is 12 + 12 = 24.

So. 6 x 4 = 24.

**Independent Practice**

**Double a known fact to find each product. Draw and label an array.**

Question 2.

8 × 4 = ______________

Answer:

Multiplication of 8 with 4 then you get 32.

8 x 4 = 32.

32 is the product.

Double the product is 32 + 32 = 64.

Know 8 x 4 + 8 x 4 = 16 x 4.

so, 16 x 4 = 64.

The array is

Question 3.

5 × 4 = _______________

Answer:

Multiplication of 5 with 4 then you get 20.

5 x 4 = 20.

20 is the product.

Double the product is 20 + 20 = 40.

Know add 5 x 4 + 5 x 4 = 10 x 4

So, 10 x 4 = 40.

The array is

Question 4.

4 × 6 = _______________

Answer:

Multiplication of 4 with 6 then 24.

4 x 6 = 24.

24 is the product.

Know double the product.

24 + 24 = 48.

Add 4 x 6 + 4 x 6 = 8 x 6

So, 8 x 6 = 48.

The array is

Question 5.

7 × 4 = ________________

Answer:

Multiplication of 7 with 4 then you get 28.

7 x 4 = 28.

28 is the product.

Know double the product.

28 + 28 = 56

Add 7 x 4 + 7 x 4 = 14 x 4

So, 14 x 4 = 56.

The array is

**Algebra Find each unknown. Double a known fact.**

Question 6.

7 × 4 =

The unknown is _______________.

Answer:

Multiplication of 7 with 4 then you get 28.

28 is the product.

The unknown is 28.

Double the unknown is 28 + 28 = 56.

Question 7.

9 × 4 =

The unknown is ________________.

Answer:

Multiplication of 9 with 4 then you get 36.

9 x 4 = 36.

36 is the product.

The unknown is 36.

Double the unknown is 36 + 36 = 72.

Question 8.

The unknown is ________________.

Answer:

16 is the product.

The unknown is 16.

Double the product is 16 + 16 = 32

Question 9.

The unknown is ________________.

Answer:

The product is 40.

The unknown is 40.

Double the product is 40 + 40 = 80.

**Problem Solving**

Question 10.

The library offers 4 activities on Saturday. Each activity table has room for 10 children. How many children can take part in the activities? Write a multiplication sentence to solve.

Answer:

The library offers 4 activities on Saturday.

Each activity table has room for 10 children.

The multiplication sentence is 4 x 10 = 40.

Therefore the children can take part in the activities are 40.

Question 11.

**Mathematical PRACTICE** Reason Mitch bought 4 bottles of suntan lotion for $6 each. Later the lotion went on sale for $4 each. How many more bottles could he have bought for the same amount of money if he waited for the sale?

Answer:

Given that,

Mitch bought 4 bottles of suntan lotion for $6 each.

The cost of 4 bottles is $6 x 4 = $24.

Later the lotion went on sale for $4 each.

Known the cost of 4 bottles is $4 x 4 = $16.

So, $24 – $16 = $8.

For $8 we get 2 bottles.

Therefore he can buy 2 many more bottles if he waited for the sale.

**HOT Problems**

Question 12.

**Mathematical PRACTICE** Use Number Sense Look at the multiplication table. Circle the two numbers that represent the product of 4 and 10. Write this product as a sum of two equal addends.

Can the product of 4 and any number always be written as a sum of two equal addends? Explain.

Answer:

The product of 4 and 10 is 40.

4 x 10 = 40.

Sum of two equal addends is 20 + 20 = 40.

Yes, the product of 4 and any number always be written as a sum of two equal addends.

It is 2 x 6 = 12.

Equal addends is 6 + 6 = 12.

Question 13.

**Building on the Essential Question** What is one strategy I could use to multiply by 4?

Answer:

We know that 2 x 2 = 4.

To multiply a number 4 we can multiply two twice.

Is 2 x 2 + 2 x 2 = 4 x 2.

### McGraw Hill My Math Grade 3 Chapter 7 Lesson 4 My Homework Answer Key

**Practice**

**Double a known fact to find the product. Label the array and complete the number sentences.**

Question 1.

4 × 5

__________ + ____________ = ___________

So, 4 × 5 = _____________.

Answer:

The product is 10.

Double the product is 10 + 10 = 20.

So, 4 x 5 = 20.

Question 2.

3 × 4

__________ + ____________ = ___________

So, 3 × 4 = _____________.

Answer:

6 is the product.

Know add the product 6 + 6 = 12.

So, 3 x 4 = 12.

**Double a known fact to find each product. Draw and label an array.**

Question 3.

6 × 4 = ______________

Answer:

Multiplication of 6 with 4 then you get 24.

6 x 4 = 24.

6x 4 + 6 x 4 = 12 x 4.

The product is 24.

Double the product is 24 + 24 = 48.

The array is

Question 4.

4 × 8 = ______________

Answer:

Multiplication of 4 with 8 then you get 32.

4 x 8 = 32.

4 x 8 + 4 x 8 = 8 x 8

The product is 32.

Double the product is 32 + 32 = 46.

The array is

**Algebra Find each unknown. Double a known fact.**

Question 5.

9 × 4 =

The unknown is _______________.

Answer:

Multiplication of 9 with 4 then you get 36.

9 x 4 = 36.

The product is 36.

The unknown is 36

Double the unknown is 36 + 36 = 72.

Question 6.

4 × 4 =

The unknown is _______________.

Answer:

Multiplication of 4 with 4 then you get 16.

4 x 4 = 16.

The product is 16.

The unknown is 16.

Double the unknown is 16 + 16 = 32.

**Problem Solving**

Question 7.

**Mathematical PRACTICE** Model Math Melissa owns 4 sets of jewelry. Each set contains 2 earrings, 1 necklace, 1 bracelet, and 1 ring. How many pieces of jewelry does Melissa have altogether? Write a multiplication sentence.

Answer:

Given that,

Melissa owns 4 sets of jewelry.

Each set contains 2 earrings, 1 necklace, 1 bracelet, and 1 ring.

The number of pieces in each set is 5.

So, the multiplication sentence is 4 x 5 = 20.

Therefore the number of pieces of jewelry does Melissa have altogether is 20.

**Vocabulary Check**

**Write a definition for the vocabulary word(s).**

Question 8.

known fact ___________________

Answer:

A fact that you have memorized is a known fact.

Question 9.

decompose ___________________

Answer:

Decompose means break down numbers into parts.

**Test Practice**

Question 10.

There are 7 birdfeeders at the park. Each birdfeeder has 4 perches. How many birds can use the birdfeeders at the same time?

(A) 32 birds

(B) 28 birds

(C) 11 birds

(D) 3 birds

Answer:

Given that,

There are 7 birdfeeders at the park.

Each birdfeeder has 4 perches.

Birds can use the birdfeeders at the same time is 7 x 4 = 28.

Option B is the correct answer.