How to add and subtract fractions
Give the fractions a common denominator, then add or subtract the numerators. The quickest common denominator is the product of the two denominators; the answer is then reduced.
a/b + c/d = (a×d + c×b) ÷ (b×d) 1/2 + 2/3 = (3 + 4) ÷ 6 = 7/6 = 1 1/6
How to multiply and divide fractions
Multiply straight across: numerators together, denominators together. To divide, flip the second fraction and multiply.
a/b × c/d = ac/bd a/b ÷ c/d = a/b × d/c
Mixed numbers
Turn a mixed number into an improper fraction first: multiply the whole number by the denominator and add the numerator. 2 1/4 becomes 9/4.
Common fractions as decimals
| Fraction | Decimal | Percent |
|---|---|---|
| 1/8 | 0.125 | 12.5% |
| 1/4 | 0.25 | 25% |
| 1/3 | 0.333… | 33.3% |
| 3/8 | 0.375 | 37.5% |
| 1/2 | 0.5 | 50% |
| 5/8 | 0.625 | 62.5% |
| 2/3 | 0.666… | 66.7% |
| 3/4 | 0.75 | 75% |
| 7/8 | 0.875 | 87.5% |
Frequently asked questions
How do I simplify a fraction?
Divide the numerator and denominator by their greatest common factor. 18/24: both divide by 6, giving 3/4.
Can the answer be a whole number?
Yes. If the numerator divides evenly by the denominator, the calculator shows a whole number, such as 8/4 = 2.