1.8 Decimals and Rounding Review

Learning Objectives

  • Read and write decimal numbers.
  • Identify the place value of digits in a decimal.
  • Round decimals to a given place.

 

Understanding Decimals

A decimal represents a part of a whole. The digits to the right of the decimal point show fractional values.

A decimal place value chart displayed in a table format with labeled columns extending from hundred thousands on the left to hundred-thousandths on the right. The chart includes columns for hundred thousands, ten thousands, thousands, hundreds, tens, and ones on the whole number side, followed by a decimal point, then tenths, hundredths, thousandths, ten-thousandths, and hundred-thousandths on the fractional side. Each column shows its corresponding value (for example, 100,000, 10,000, 1,000, 100, 10, 1, then 1/10, 1/100, 1/1,000, etc.). Brackets and arrows group the columns into a “Whole number part” on the left and a “Fractional part” on the right, with the decimal point labeled in the center as “read ‘and’.”
Figure 1.8

 

Table 1.8
Place Value Example in 3.472
Ones 3
Tenths 4
Hundredths 7
Thousandths 2

The value of 3.472 is:

  • 3 ones
  • 4 tenths
  • 7 hundredths
  • 2 thousandths

Reading and Writing Decimals

Example 1.8.1

Write 4.56 in words.

Solution

four and fifty-six hundredths

 

Example 1.8.2

Write “seven and three tenths” as a decimal.

Solution

7.3

Decimals as Fractions

Decimals can be written as fractions.

Example 1.8.3

Write 0.75 as a fraction.

Solution

0.75 = \frac{75}{100} = \frac{3}{4}

 

Example 1.8.4

Write 2.4 as a mixed number.

Solution

2.4 = 2\frac{4}{10} = 2\frac{2}{5}

Rounding Decimals

To round a decimal:

  1. Identify the place you are rounding to.
  2. Look at the digit to the right.
  3. If it is 5 or greater, round up.
  4. If it is less than 5, keep it the same.

Example 1.8.5

Round 3.476 to the nearest hundredth.

Solution
  • Hundredths place = 7
  • Look at the thousandths place: 6
  • Since 6 is 5 or greater, round up.

Answer: 3.48

 

Example 1.8.6

Round 8.231 to the nearest tenth.

Solution
  • Tenths place = 2
  • Look at the hundredths place: 3
  • Since 3 is less than 5, keep the tenths digit the same.

Answer: 8.2

 

Try It

 

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Essentials of Mathematics Copyright © 2026 by Scott McDaniel is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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