Rounding Decimals – Definition, Types, & Examples
Key Concepts
- Rounding decimals to the nearest whole number.
- Express fractions as a decimal.
- Express decimals as a fraction.
- Equivalent fractions.
Rounding Decimals:
Rounding decimals to the nearest whole number or tenth.
Rounding is a process to estimate a particular number in the context. We can round decimals to the nearest wholes, tenths, or hundredths.
Rules for rounding decimals to the nearest whole number:
- To round a decimal to the nearest whole number, analyze the digit at the first decimal place, i.e., tenths place.
- If the tenths place value is 5 or greater than 5, then the digit at the ones place is increased by 1, and the digit at the tenths place becomes zero.
- If the tenths place value is less than 5, then the digit at the ones place remains the same, but the digits at the tenths place become zero.
Example: Round off 24.77 to the nearest whole number.
Sol:
Example:
(a) Round off 51.7 to the nearest whole number.
Sol: 51.7
The digit at the tenths place is 7.
7 > 5
The whole number part of 51.7 is increased by one.
51.7 rounded off to the nearest whole number as 52.
(b) Round 11.04 to the nearest tenths
Sol: 11.04
The digit at hundredths place is 4, and:
4 < 5
11.04 rounded off to the nearest tenths is 11.
Fractions and decimals
Express fraction as a decimal
To convert a fraction to a decimal, divide the numerator by the denominator.
Example: What is 
as a decimal.
Sol: = 0.125
Express decimal as a fraction.
To convert a decimal to a fraction, place the decimal number over its place value.
Example:
Example: Express 0.9 as fraction
Sol: 0.9 = 
Equivalent fractions.
Equivalent fractions: Equivalent fractions can be defined as fractions that may have different numerators and denominators but represent the same value.
Example: 
and 
are equivalent because both are equal to 
.
= 
=
Therefore, 
=
Exercise:
- Write 205.9 in the place value table.
- Write seven-tenths as a decimal.
- Write 3 + 7/10 as a decimal.
- Write 2.5 as a fraction.
- Write 4/5 as a decimal.
- Write 2.34 in the lowest terms.
- Write 50 + 1/10 + 6/10 in decimal form.
- Compare 1.09 or 1.093. Which is greater?
- Compare 1.23 or 1.2. Which is smaller?
- Round 1.76 to the nearest whole number.
- Round 1.42 to the nearest tenths.
- Write the numbers from the smallest to the largest: 51.5, 59.0, 39.2, 84.4.
- Write the numbers from the largest to the smallest: 60.9, 66.6, 96.2, 90.5.
- Find the next two numbers in the pattern of 2.1, 2.4, 2.7, 3, 3.3, 3.6, 3.9.
- Express 2/9 as a decimal.
What have we learnt:
- Introduction of decimals.
- How the place value of a digit changes when we multiply or divide it by ten.
- How to read, write, and model fractions with 10 and 100 in the denominator.
- How to compare decimals from the least to the greatest and from the greatest to the least.
- Ordering of decimals.
- How to round decimals to the nearest whole numbers.
- How to express a fraction as a decimal and a decimal as a fraction.
Concept Map
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