All the solutions provided in **McGraw Hill Math Grade 4 Answer Key PDF Chapter 5 Lesson 1 Multiply by Tens** will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 4 Answer Key Chapter 5 Lesson 1 Multiply by Tens

**Math in My World**

Example 1

Miss Rita took 20 pictures at the zoo. She printed the pictures so that each of her 25 students could have a copy. How many pictures did Miss Rita print?

Find 25 × 20.

The number 20 is a multiple of ten.

**One Way** Use properties.

Think of 20 ___ as × 1o.

25 × 20 = 25 × (___ × ____)

= (25 × 2) × 10

= 50 × 10 = ____

You have used the Associative Property of Multiplication.

**Another Way** Use paper and pencil.

1. Multiply the ones.

2. Multiply the tens.

Answer: Miss Rita prints 500 pictures.

Explanation: Given that,

Miss Rita took 20 pictures at the zoo.

She printed the pictures so that each of her 25 students could have a copy.

Now, we will find out how many pictures did Miss Rita print.

There are 2 methods for finding the value.

First Method:

The number 20 is a multiple of ten.

One Way Use properties.

25 × 20 = 25 × ( 2× 10)

= (25 × 2) × 10

= 50 × 10 = 500

You have used the Associative Property of Multiplication.

Second Method: Multiply the given values.

First, multiply the ones

Next, multiply with tens.

Hence, the product value is 500. Therefore Miss Rita prints 500 Pictures.

Example 2

An electronics store has 30 digital music players in stock that cost $99 each. How much do the digital music players cost altogether?

You need to find $99 × 30. The number 30 is a multiple of 10.

1. Multiply the ones.

0 ones × 99 = _____

2. Multiply the tens.

3 tens × 99 = ___tens

So, the music players cost a total of $ ____.

Answer: So, the music players cost a total of $ 2970.

0 x $99 = 0

3 x $99 = 297

Explanation: Given the data is,

An electronics store has 30 digital music players in stock that cost $99 each.

Now, we will find out how much digital music players cost altogether.

So, the values are 99 and 30.

First, Multiply with ones.

0 ones x 99 = 0

Next, multiply with tens

3 tens x 99 = 297

Hence, the cost of altogether digital music players is $2970.

**Helpful Hint**

When you multiply a number by a multiple of 10, the digit in the ones place is always zero.

**Talk Math**

Joey is finding 67 × 40. Explain why he can think of 67 × 40 as 67 × 4 × 10.

Answer: Joey is finding 67 x 40 because we can multiply it directly its some difficult. So, if we use 67 x 4 x 10 we can easily multiply in this way too by using a multiple of tens the one’s digit will always be zero. Then we can fastly calculate the product value.

**Guided Practice**

**Multiply.**

Question 1.

Answer: 360

Explanation: Given the values are 36 and 10.

Now, we will find the product value.

So, multiply the given values i.e.,

36 x 10 = 360.

Hence, the product value is 360.

Question 2.

Answer: 1590

Explanation: Given the values are 53 and 30.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is 1590.

Question 3.

Answer: 840

Explanation:

Given the values are 42 and 20.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product value is 840.

Question 4.

Answer: 2560

Explanation:

Given the values are 64 and 40.

Now, we will find the product value.

So, multiply the given values i.e.,

After multiplication, the product value is 2560.

**Independent Practice**

**Multiply.**

Question 5.

Answer: 300

Explanation:

Given the values are 15 and 20.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product of given values is 300.

Question 6.

Answer: 810

Explanation:

Given the values are 27 and 30.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is 810.

Question 7.

Answer: 1840

Explanation:

Given the values are 46 and 40.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is 1840.

Question 8.

53 × 60 = ____

Answer: 3180

Explanation:

Given the values are 53 and 60.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product value is 3180.

Question 9.

80 × 80 = ____

Answer: 6400

Explanation:

Given the values are 80 and 80.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is 6400.

Question 10.

94 × 90 = ____

Answer: 8460

Explanation:

Given the values are 94 and 90.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is 8460.

Question 11.

$27 × 10 = ____

Answer: $270

Explanation:

Given the values are $27 and 10.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product value is $270.

Question 12.

$31 × 30 = ___

Answer: $930

Explanation:

Given the values are $31 and 30.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product of given values is $930.

Question 13.

$38 × 50 = ____

Answer: $1900

Explanation:

Given the values are $38 and 50.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is $1900.

Question 14.

$45 × 50 = ___

Answer: $2250

Explanation:

Given the values are $45 and 50.

Now, we will find the product value.

So, multiply the given values i.e.,

Therefore, the product value is $2250.

Question 15.

$56 × 70 = ___

Answer: $3920

Explanation: Given the values are $56 and 70.

Now, we will find the product value.

So, multiply the given values i.e.,

Hence, the product of given values is 3920.

Question 16.

$69 × 80 = ___

Answer: $5520

Explanation:

Given the value is $69 and 80.

Now, we will find the product value.

Multiply the given values i.e.,

Thus, the product value is 5520.

Question 17.

If 7 × 29 = 203, then what is 70 × 29?

Answer: 70 x 29 = 2030.

Explanation:

Given that,

7 x 29 = 203.

Now, we will find the value of 70 x 29.

So, the value is 70 and 29. Multiply it.

Hence, the value of 70 x 29 is 2030.

Question 18.

If 3 × 52 = 156, then what is 30 × 52?

Answer:

30 x 52 = 1560.

Explanation: Given that,

3 x 52 = 156.

Now, we will find the value of 30 x 52.

So, the values are 30 and 52. Multiply it.

Therefore, the product of 30 x 52 is 1560.

**Algebra Use mental math to find the unknown number.**

Question 19.

22 × y = 440

y = ____

Answer: y = 20

Explanation:

Given that, the equation is 22 x y = 440.

Now, we will find the unknown number i.e., y value.

So, the value is 22 x y = 440

i.e., y = 440/22

Now, divide it. To get the quotient value that is y value.

Therefore, the value of y is 20.

Question 20.

15 × y = 450

y = ____

Answer: y = 30

Explanation:

Given that, the equation is 15 x y = 450.

Now, we will find the unknown number i.e., y value.

So, the value is 15 x y = 450

i.e., y = 450/15

Now, divide it. To get the quotient value that is y value.

Therefore, the value of y is 30.

Question 21.

25 × z = 500

z = ____

Answer: z = 20

Explanation:

Given that, the equation is 25 x z = 500.

Now, we will find the unknown number i.e., z value.

So, the value is 25 x z = 500

i.e., z = 500/25

Now, divide it. To get the quotient value that is z value.

Hence, the value of z is 20.

**Problem Solving**

Hummingbirds feed every 10 minutes. They fly about 25 miles per hour and flap their wings 60 to 80 times each second.

Question 22.

What is the least number of times a hummingbird will flap its wings in 15 seconds?

Answer:

The least number of times a hummingbird will flap its wings in 15 seconds is 900 times.

Explanation:

Given that,

A hummingbird flaps its wings 60 to 80 times per second.

Now, we will find the greatest number of times. So, we can consider the 60 times because its a least value.

So, the value is 60 and 15. Multiply it.

Therefore, the least number of times is 900 times.

Question 23.

What is the greatest number of times a hummingbird will flap its wings in 15 seconds?

Answer:

The greatest number of times a hummingbird will flap its wings in 15 seconds is 1200 times.

Explanation:

Given that,

A hummingbird flaps its wings 60 to 80 times per second.

Now, we will find the greatest number of times. So, we can consider the 80 times because its a greater value.

So, the value is 80 and 15. Multiply it.

Hence, the greatest number if times is 1200.

Question 24.

How many minutes have passed if a hummingbird has eaten 45 times?

Answer: 450 minutes have passed if a hummingbird has eaten 45 times.

Explanation:

Given that,

A hummingbird feeds every 10 minutes.

So, if the bird eats 45 times then,

45 x 10 = 450 minutes.

Question 25.

**Mathematical PRACTICE 4 Model Math** If a hummingbird flies a total of 20 hours, how far did it fly? Write a number sentences to describe your answer.

Answer: The hummingbird flies 500 miles. 20 x 25 = 500 miles.

Explanation:

Given that,

A hummingbird flies for a total of 20 hours.

Each hour it files 25 miles

Now, we will find out how far did it fly.

The values are 20 and 25. Multiply it.

Hence, for 20 hours the hummingbird flies 500 miles.

**HOT Problems**

Question 26.

Mathematical PRACTICE 3 Which One Doesn’t Belong? Circle the multiplication problem that does not belong with the other three. Explain.

Answer: 41 x 21. Because it doesn’t belong to multiple of ten. The 41 x 20 represents multiplication by a multiple of ten. The remaining 3 is a multiple of tens multiplication.

Question 27.

**? Building on the Essential Question** How can place value help me multiply a two-digit number by a multiple of ten?

Answer: When multiplying by a multiple of ten, the digit in the ones place is always zero.

### McGraw Hill My Math Grade 4 Chapter 5 Lesson 1 My Homework Answer Key

**Practice**

**Multiply.**

Question 1.

Answer: 1530

Explanation:

Given the values are 51, 30.

Now, we will find the product value.

So, the multiplication of 51 and 30 is,

Therefore, the product value is 1530.

Question 2.

Answer: 3120

Explanation:

Given the values are 39 and 80.

Now, we will find the product value.

So, the multiplication of 39 and 80 is,

Therefore, the product value is 3120.

Question 3.

Answer: 1500

Explanation:

Given the values are 25, 60

Now, we will find the product valie.

So, the multiplication of 25 and 60 is,

Hence, the product value is 1500.

Question 4.

Answer: 2100

Explanation:

Given the value is 42 and 50.

Now, we will find the product value.

So, the multiplication of 42 and 50 is,

Hence, the product value is 2100.

Question 5.

Answer: 4050

Explanation:

Given the values are 45 and 90.

Now, we will find the product value.

So, the multiplication of 45 and 90 is,

Hence, the product value is 4050.

Question 6.

Answer: 2640

Explanation:

Given the values are 88 and 30.

Now, we will find the final multiplication value.

So, the multiplication is,

Therefore, the product value is 2640.

Question 7.

68 × 40 = ____

Answer: 2720

Explanation:

As given in the question, the value is 68 and 40.

Now, we will find the product value.

So, the multiplication is,

Hence, the product of given values is 2720.

Question 8.

11 × 70 = ____

Answer: 770

Explanation:

Given the value is 11 and 70.

Now, we will find the product value.

So, the multiplication value is 11 and 70,

Hence, after multiplication, the product value is 770.

Question 9.

99 × 10 = ____

Answer: 990

Explanation:

Given the values are 99 and 10.

Now we will find the product value.

So, the multiplication of 99 and 10 is,

Hence, the product of the given values is 990.

**Problem Solving**

Question 10.

There are 40 rows of lockers. There are 12 lockers in each row. How many lockers are there?

Answer: 480 lockers are there.

Explanation:

Given that,

There are 40 rows of lockers.

There are 12 lockers in each row.

Now, we need to find the number of lockers are there.

So, the values are 40 and 12. The multiplication is,

Hence, 480 lockers are there.

Question 11.

Pablo found out that every classroom has 34 desks. There are 30 classrooms. How many desks are in the school?

Answer: 1020 desks are in the school.

Explanation:

As given in the question,

Pablo found out that every classroom has 34 desks.

There are 30 classrooms. How many desks are in the school?

Now, we will find how many desks are in the school.

So, the value is 34 and 30. Multiply the values we get the product value.

The multiplication is,

Therefore, 1020 desks are there in the school.

Question 12.

It costs $10 per person to enter the museum. How much money would it cost for 30 people to enter the museum?

Answer: $300 cost for 30 people to enter the museum.

Explanation:

As given in the question,

It costs $10 per person to enter the museum.

Now, we will find how much money for 30 people to enter the museum.

So, the value is $ 10 30.

i.e., $10 x 30 = $300.

Therefore, for 30 people to enter the museum the cost is $300.

Question 13.

**Mathematical PRACTICE 6 Be Precise** Use the Commutative Property to find the unknown number in equation 35 × 70 = m × 35.

Answer: Use the commutative property the unknown number in the equation is m = 70. Because in this property, the product values will be the same but the places will be changed. So, the value of m is 70.

Question 14.

**Algebra **Use mental math to find the unknown number in equation 12 × b = 480.

Answer: The unknown number b = 40

Explanation:

Given the equation is 12 x b = 480.

Now, we will find the unknown number value.

So, the value is 12 x b = 480.

b = 480/12

Hence, the quotient value is the unknown number value. Therefore the value of b is 40.

**Test Practice**

Question 15.

To raise money for an animal shelter, 17 students ran in a race. Each student raised $30. How much did the students raise in all?

A. $47

B. $51

C. $310

D. $510

Answer: Option D

Explanation:

As given in the question,

To raise money for an animal shelter, 17 students ran in a race.

Each student raised $30.

Now, we will find how much money students raise in all.

So, the value is 17 and 30. Multiply the values we get the product value.

The multiplication is,

Therefore, all students raised $510. Hence, option D is correct.