Rounding Decimals

Use place value understanding to round decimals to any place. Use

place value understanding to round decimals to any place.

5.NBT.4

Where do we see Decimals being used? Look behind the photos to find out!

Decimals are used in swimming times to get the most accurate results. A typical swim time measures minutes, seconds, and fractions of a second. Example: 1:52.28

Basketball shooting percentages use decimals to show how often players make shots. Example: 0.421

Scientists use decimals to show more accurate measurements in their data. This helps them to notice small changes in the data.

You use decimals when talking about money. The change is expressed after the decimal point as in $1.62.

Decimals on the Number Line

2 3

What does each line represent on this number line between the whole numbers of 2 and 3?

Label the number line.

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

4.3 4.4

What does each line represent on this number line between the decimal numbers of 4.3 and 4.4?

Label the number line.

4.31

4.32

4.33

4.34

4.35

4.36

4.37

4.38

4.39

Decimals on the Number Line

Where would you place 4.4 on this number line?

A B C D0 10

4 5

Rounding 2.728 to the nearest whole number

2 3

2.5

2.5 is in the middle of 2 and 3. On which side of the hill would 2.728 be?

Is 2.728 closer to 2 or to 3?

2 3

2.728

Is 2.728 closer to 2 or to 3?

Rounding 2.728 to the nearest whole number

2.7 2.8

2.75

2.75 is in the middle of 2.7 and 2.8On which side of the hill would 2.728 be?

Is 2.728 closer to 2.7 or to 2.8?

Rounding 2.728 to the nearest tenth

2.7 2.8

2.728

Is 2.728 closer to 2.7 or to 2.8?

Rounding 2.728 to the nearest tenth

2.72

2.73

2.725

2.725 is in the middle of 2.72 and 2.73 On which side of the hill would 2.728 be? Is 2.728 closer to 2 or to 3?

Rounding 2.728 to the nearest hundredth

Rounding 2.728 to the nearest hundredth

2.72 2.73

2.728

Is 2.728 closer to 2.72 or to 2.73?

Rounding 6.293 to the nearest whole number

.

6 7

6.5

6.5 is in the middle of 6 and 7Which side of the hill would 6.293 be on?

Is 6.293 closer to 6 or 7?

Rounding 6.293 to the nearest whole number

.

6 7

6.293

Is 6.293 closer to 6 or to 7?

Rounding 6.293 to the nearest tenth

.

6.2

6.3

6.25

6.25 is in the middle of 6.2 and 6.3 Which side of the hill would 6.293 be on? Is 6.293 closer to 6.2 or 6.3?

Rounding 6.293 to the nearest tenth

.

6.2 6.3

6.293

Is 6.293 closer to 6.2 or to 6.3?

Rounding 6.293 to the nearest hundredth

.

6.29

6.3

6.295

6.295 is in the middle of 6.29 and 6.3Which side of the hill would 6.293 be on?

Is 6.293 closer to 6.29 or 6.3?

Rounding 6.293 to the nearest tenth

.

6.29

6.3

6.293

Is 6.293 closer to 6.2 or to 6.3?

Round each number to the nearest hundredth

a. 4.025    b. 6.088    c. 3.202     d. 4.116     e. 2.066    f. 1.908

David swam 2.549 miles. He rounded his distance to 3 miles. His coach rounded his

distance to 2.5 miles.

Explain how this could be true. Use number lines and words to explain

your reasoning.

Both are right!