Math
How to Convert Fractions to Decimals (With Examples)
Why Convert Fractions to Decimals?
Fractions and decimals are two ways of expressing the same value. Converting between them is essential for:
- Comparing numbers: Is 3/8 bigger than 0.4? Converting to decimals makes comparisons instant.
- Calculators and computers: Most technology works with decimals, not fractions.
- Real-world applications: Money, measurements, and statistics use decimals.
- Standardized tests: Many exam questions require you to convert between formats.
The good news? The process is simple — it's just division.
The Division Method
To convert any fraction to a decimal, divide the numerator by the denominator.
Formula: a/b = a ÷ b
Example 1: Convert 3/4 to a decimal
3 ÷ 4 = 0.75
Example 2: Convert 7/8 to a decimal
7 ÷ 8 = 0.875
Example 3: Convert 1/3 to a decimal
1 ÷ 3 = 0.333... (repeating)
Tip: If you don't have a calculator, use long division. Place a decimal point after the numerator and add zeros, then divide normally.
Long division walkthrough: 5/8
- 5 ÷ 8 = 0 remainder 5
- 50 ÷ 8 = 6 remainder 2
- 20 ÷ 8 = 2 remainder 4
- 40 ÷ 8 = 5 remainder 0
Result: 5/8 = 0.625
Common Fraction-to-Decimal Conversions
Memorizing these common conversions saves time on tests:
| Fraction | Decimal | |---|---| | 1/2 | 0.5 | | 1/3 | 0.333... | | 1/4 | 0.25 | | 1/5 | 0.2 | | 1/8 | 0.125 | | 1/10 | 0.1 | | 2/3 | 0.666... | | 3/4 | 0.75 | | 2/5 | 0.4 | | 3/5 | 0.6 | | 3/8 | 0.375 | | 5/8 | 0.625 | | 7/8 | 0.875 |
Pro tip: If the denominator is a power of 10 (10, 100, 1000), the conversion is instant. For example, 47/100 = 0.47.
Repeating Decimals
Some fractions produce decimals that never end — they repeat a pattern forever. These are called repeating decimals.
Examples:
- 1/3 = 0.333... (written as 0.3̄)
- 1/6 = 0.1666... (written as 0.16̄)
- 2/7 = 0.285714285714... (written as 0.2̄8̄5̄7̄1̄4̄)
- 1/9 = 0.111... (written as 0.1̄)
How to identify repeating decimals
A fraction produces a terminating decimal (one that ends) only if the denominator's prime factors are limited to 2 and 5. Otherwise, it will repeat.
- 1/4 = 0.25 ✅ terminates (4 = 2²)
- 1/8 = 0.125 ✅ terminates (8 = 2³)
- 1/3 = 0.333... ❌ repeats (3 is not 2 or 5)
- 1/6 = 0.1666... ❌ repeats (6 = 2 × 3)
Rounding repeating decimals
For practical purposes, round to the required number of decimal places:
- 1/3 ≈ 0.33 (rounded to 2 places)
- 2/3 ≈ 0.67 (rounded to 2 places)
Mixed Numbers to Decimals
A mixed number like 3 1/4 has a whole number part and a fraction part.
Method: Convert the fraction part to a decimal and add it to the whole number.
- 3 1/4 = 3 + 0.25 = 3.25
- 5 3/8 = 5 + 0.375 = 5.375
- 2 1/3 = 2 + 0.333... = 2.333...
Alternatively, convert the mixed number to an improper fraction first, then divide:
- 3 1/4 = 13/4 = 13 ÷ 4 = 3.25
Both methods give the same result.
Practice Problems
Convert these fractions to decimals:
- 5/8
- 2/5
- 7/20
- 4 3/4
- 5/6
Answers: (1) 0.625 (2) 0.4 (3) 0.35 (4) 4.75 (5) 0.8333...
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