How to Round a Number to the Nearest Tenth (1 Decimal Place)

Place Value Review

Notice the decmal point. All places to the right of the decimal end with “ths”

ths

For you notebook (copy this):

• Rounding Decimals: to round a decimal to a given place value, look at the digit in the place to the right.

• If the digit is 4 or less, round down.• If the digit is 5 or greater, round up.

First look at the value of the digit in the hundredths column

4.675 Has 7 hundredths

First look at the value of the digit in the hundredths column

4.675 Has 7 hundredths

5.85 Has 5 hundredths

First look at the value of the digit in the hundredths column

4.675 Has 7 hundredths

5.85 Has 5 hundredths

3.7298 Has 2 hundredths

First look at the value of the digit in the hundredths column

4.675 Has 7 hundredths

5.85 Has 5 hundredths

3.7298 Has 2 hundredths

4.23045 Has 3 hundredths

You round down to the nearest tenth if the hundredths digit is 0,1,2,3 or 4.

3.726 is rounded down to 3.7

You round down to the nearest tenth if the hundredths digit is 0,1,2,3 or 4.

3.726 is rounded down to 3.7

4.23 is rounded down to 4.2

You round down to the nearest tenth if the hundredths digit is 0,1,2,3 or 4.

3.726 is rounded down to 3.7

4.23 is rounded down to 4.2

17.5178 is rounded down to 17.5

You round down to the nearest tenth if the hundredths digit is 0,1,2,3 or 4.

3.726 is rounded down to 3.7

4.23 is rounded down to 4.2

17.5178 is rounded down to 17.5

120.60124 is rounded down to 120.6

You round down to the nearest tenth if the hundredths digit is 0,1,2,3 or 4.

3.726 is rounded down to 3.7

4.23 is rounded down to 4.2

17.5178 is rounded down to 17.5

120.60124 is rounded down to 120.6

45.44008 is rounded down to 45.4

You round up to the nearest tenth if the hundredths digit is 5,6,7,8 or 9.

4.67 is rounded up to 4.7

You round up to the nearest tenth if the hundredths digit is 5,6,7,8 or 9.

4.67 is rounded up to 4.7

5.8577 is rounded up to 5.9

You round up to the nearest tenth if the hundredths digit is 5,6,7,8 or 9.

4.67 is rounded up to 4.7

5.8577 is rounded up to 5.9

17.7802 is rounded up to 17.8

You round up to the nearest tenth if the hundredths digit is 5,6,7,8 or 9.

4.67 is rounded up to 4.7

5.8577 is rounded up to 5.9

17.7802 is rounded up to 17.8

125.29 is rounded up to 125.3

You round up to the nearest tenth if the hundredths digit is 5,6,7,8 or 9.

4.67 is rounded up to 4.7

5.8577 is rounded up to 5.9

17.7802 is rounded up to 17.8

125.29 is rounded up to 125.3

46.36445 is rounded up to 46.4

Watch out for numbers which have 9 in the tenths column.

e.g. 2.97If you are rounding up, you will make 10 tenths. This makes 1 unit, so you have to round to the next whole number (in this case to 3).

Watch out for numbers which have 9 in the tenths column.

e.g. 2.97If you are rounding up, you will make 10 tenths. This makes 1 unit, so you have to round to the next whole number (in this case to 3).

For the same reason, 23.964 becomes 24

Watch out for numbers which have 9 in the tenths column.

e.g. 2.97If you are rounding up, you will make 10 tenths. This makes 1 unit, so you have to round to the next whole number (in this case to 3).

For the same reason, 23.964 becomes 24

12.9505 becomes 13

Watch out for numbers which have 9 in the tenths column.

e.g. 2.97If you are rounding up, you will make 10 tenths. This makes 1 unit, so you have to round to the next whole number (in this case to 3).

For the same reason, 23.964 becomes 24

12.9505 becomes 13

And 6.98 becomes 7

EXAMPLE 1 Using a Number Line to Round

Use a number line to round 3.87 to the nearest tenth.

EXAMPLE 1 Using a Number Line to Round

Use a number line to round 3.87 to the nearest tenth.

EXAMPLE 1 Using a Number Line to Round

Use a number line to round 3.87 to the nearest tenth.

ANSWER

EXAMPLE 1 Using a Number Line to Round

Use a number line to round 3.87 to the nearest tenth.

The decimal 3.87 rounds up to 3.9.

ANSWER

GUIDED PRACTICE

Use a number line to round the decimal as specified.

for Example 1

GUIDED PRACTICE

Use a number line to round the decimal as specified.

1. 1.3 (nearest one)

for Example 1

GUIDED PRACTICE

Use a number line to round the decimal as specified.

1. 1.3 (nearest one)

for Example 1

1 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 1. 7 1. 8 1.9 2.0

GUIDED PRACTICE

Use a number line to round the decimal as specified.

1. 1.3

The decimal 1.3 is closer to 1 than to 3

GUIDED PRACTICE

(nearest one)

for Example 1

1 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 1. 7 1. 8 1.9 2.0

GUIDED PRACTICE

ANSWER

The decimal 1.3 rounds down to 1.

GUIDED PRACTICE for Example 1

Use a number line to round the decimal as specified.

1. 1.3 (nearest one)

The decimal 1.3 is closer to 1 than to 3

1 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 1. 7 1. 8 1.9 2.0

That’s it for now......