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Chapter 4—Decimals

4-2 Rounding Decimals

When you complete the work for this section, you should be able to:
  • Round decimal fractions at any given place value.

Rounding is especially important when working with decimal fractions. When doing long division with decimal values, for example, it is quite possible to come up with decimal answers that have an endless number of digits in the fraction part. In such instances, you must end the sequence of digits at some reasonable point—or, in other words, round off the result.

Example 1

Problem

Round 2.31862 to the nearest hundredth.

Solution

Step 1: Locate the hundredth position

2.31862

Step 2: Round up or down, according to the number immediately to the right of the specified number.

  • Round up if this number is greater or equal to 5.
  • Round down if this number is less than 5.

This number is greater than 5 so we round up:

2.31862

2.32

2.31862 rounded to the nearest hundredth is 2.32

Example 2

Problem

Round –15.716 to the nearest tenth.

Solution

Note : The negative sign does not affect the way you round numbers.

Step 1: Locate the tenths position

–15.716

Step 2: Round up or down, according to the number immediately to the right of the specified number.

  • Round up if this number is greater or equal to 5.
  • Round down if this number is less than 5.

This number is less than 5 so we the round down:

–15.716

–15.7

–15.716 rounded to the nearest tenth is –15.7.

Rounding Decimal Values

Use these interactive examples and exercises to strengthen your understanding and build your skills.

David L. Heiserman, Editor

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Revised: June 06, 2015