## Envision Math 4th Grade Textbook Answer Key Topic 2.1 Understanding Rounding

**Review What You Know**

**Vocabulary**

Choose the best term from the box.

Question 1.

In order to subtract 141 from 530, you need to __.

Answer:

Question 2.

___ tells about how many or about how much.

Answer:

Question 3.

When you subtract two numbers, the answer is the __.

Answer:

Question 4.

When you add numbers together, you find the __.

**Addition Facts**

Find the sum.

Question 5.

4 + 6

Answer:

Question 6.

7 + 5

Answer:

Question 7.

9 + 8

Answer:

Question 8.

14 + 5

Answer:

Question 9.

3 + 7

Answer:

Question 10.

37 + 7

Answer:

Question 11.

9 + 6

Answer:

Question 12.

6 + 5

Answer:

Question 13.

15 + 7

Answer:

Question 14.

3 + 8

Answer:

Question 15.

14 + 6

Answer:

Question 16.

25 + 5

Answer:

**Subtraction Facts**

Find the difference.

Question 17.

27 – 3

Answer:

Question 18.

6 – 4

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Question 19.

15 – 8

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Question 20.

11 – 8

Answer:

Question 21.

6 – 2

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Question 22.

17 – 8

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Question 23.

16 – 4

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Question 24.

20 – 5

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Question 25.

11 – 6

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Question 26.

14 – 6

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Question 27.

15 – 10

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Question 28.

13 – 7

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Question 29.

Writing to Explain Why does 843 round to 840 rather than to 850?

**Understanding Rounding**

Why do you round numbers?

Rounding __replaces one number with another number that tells about how many or how much.__

The Golden Gate Bridge’s towers reach a height of 746 feet. What is 746 rounded to the nearest ten? to the nearest hundred?

**Guided Practice***

Do you know HOW?

In 1 through 4, use a number line to round each number to the place of the underlined digit.

Question 1.

2, __2__86

Answer:

Question 2.

5,7__4__7

Answer:

Question 3.

1__5__3

Answer:

Question 4.

8,__6__39

Answer:

Do You Understand?

Question 5.

In the number lines above, why are the halfway point numbers different?

Answer:

Question 6.

In New York, the Verrazano-Narrows Bridge’s towers reach a height of 693 feet. What is 693 rounded to

the nearest ten?

Answer:

**Independent Practice**

Leveled Practice For 7 and 8, use the number line to round each number to the place of the underlined digit.

Question 7.

6__5__6

Answer:

Question 8.

9,1__2__9

Answer:

For 9 through 23, use a number line to round each number to the place of the underlined digit.

Question 9.

7,__2__41

Answer:

Question 10.

3,41__4__

Answer:

Question 11.

2,__6__39

Answer:

Question 12.

__5__61

Answer:

Question 13.

2__9__5

Answer:

Question 14.

2__0__6

Answer:

Question 15.

6,0__2__8

Answer:

Question 16.

8__7__3

Answer:

Question 17.

1__2__3

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Question 18.

1,__9__99

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Question 19.

4,__1__83

Answer:

Question 20.

6__4__7

Answer:

Question 21.

3,__8__09

Answer:

Question 22.

7__9__2

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Question 23.

8,__2__99

Answer:

Use a number line to round 746 to the nearest ten.

Compare 746 to the halfway point, which is 745.

746 is to the right of the halfway point, so round to 750.

Use a number line to round 746 to the nearest hundred.

Compare 746 to the halfway point, which is 750.

746 is to the left of the halfway point, so round to 700.

**Problem Solving**

For 24 and 25, use the table at the right.

Question 24.

Write the number of cities in each state in expanded form. Then order the numbers from greatest to least.

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Question 25.

Round each number in the table to the nearest ten. Then order the rounded numbers from least to greatest.

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Question 26.

Number Sense Write four numbers that round to 500 when rounded to the nearest hundred.

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Question 27.

The attendance at a football game at California Memorial Stadium was 54,387. What is this number rounded to the nearest hundred?

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Question 28.

At a football game, a scoreboard showed the attendance at the game to be 35,396. Which choice is this number rounded to the nearest ten?

A. 35,000

B. 35,300

C. 35,390

D. 35,400

Answer:

Question 29.

Writing to Explain Use the number line below. A car rental agency recorded the mileage of three cars in its fleet. What place

can you round each number to and still be able to accurately order the numbers? Explain.

Answer: