How to add and subtract fractions
- Find a common denominator: the least common multiple of the two bottom numbers.
- Rewrite each fraction with that denominator.
- Add or subtract the top numbers; keep the denominator.
- Simplify by dividing top and bottom by their greatest common factor.
Example: 1/2 + 1/3. The common denominator is 6, so 3/6 + 2/6 = 5/6.
How to multiply and divide fractions
- Multiply: top × top and bottom × bottom. 2/3 × 3/4 = 6/12 = 1/2.
- Divide: flip the second fraction and multiply (“keep, change, flip”). 1/2 ÷ 1/4 = 1/2 × 4/1 = 4/2 = 2.
Mixed numbers
A mixed number like 2 3/4 is a whole number plus a fraction. To calculate with it, turn it into an improper fraction: multiply the whole number by the denominator and add the numerator (2 × 4 + 3 = 11), giving 11/4. The calculator does this for you and shows the answer both ways.
Common fractions as decimals
| Fraction | Decimal | Fraction | Decimal |
|---|---|---|---|
| 1/2 | 0.5 | 1/8 | 0.125 |
| 1/3 | 0.333… | 3/8 | 0.375 |
| 2/3 | 0.666… | 1/5 | 0.2 |
| 1/4 | 0.25 | 1/10 | 0.1 |
| 3/4 | 0.75 | 1/16 | 0.0625 |
Frequently asked questions
How do I add fractions with different denominators?
Rewrite both with a common denominator (the least common multiple of the bottoms), add the tops, then simplify. 1/4 + 1/6 = 3/12 + 2/12 = 5/12.
How do I enter a mixed number?
Type the whole number, a space, then the fraction: 2 3/4. You can also type whole numbers (5) and decimals (0.75).
How do I simplify a fraction?
Divide the top and bottom by their greatest common factor. 18/24: the GCF is 6, so it simplifies to 3/4.
How do I turn a decimal into a fraction?
Write it over a power of ten and simplify: 0.375 = 375/1000 = 3/8. Use the decimal box below for repeating decimals too.
How do you divide fractions?
Flip the second fraction and multiply. 2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6.
Last updated October 2026 · More calculators