Quick start
- Enter the first value: a fraction like 5/6, a mixed number like 2 1/3 (whole number, space, fraction) or a whole number.
- Pick +, −, × or ÷.
- Enter the second value and read the steps and the answer.
Which method each operation uses
| Operation | Method | Example |
|---|---|---|
| Add | Common denominator, add the tops | 1/4 + 2/3 = 3/12 + 8/12 = 11/12 |
| Subtract | Common denominator, subtract the tops | 5/6 − 1/4 = 10/12 − 3/12 = 7/12 |
| Multiply | Top × top, bottom × bottom | 3/5 × 10/9 = 30/45 = 2/3 |
| Divide | Flip the second, then multiply | 2/3 ÷ 4/9 = 2/3 × 9/4 = 3/2 |
Example with mixed numbers
2 1/3 + 1 3/4: first turn both into improper fractions, 7/3 and 7/4. The lowest common denominator is 12, so 28/12 + 21/12 = 49/12. As a mixed number that is 4 1/12, or about 4.083.
Why common denominators matter
You can only add pieces of the same size. Thirds and quarters are different sizes, so both are cut into twelfths before adding. Multiplying does not need this step, because you are taking a part of a part.
Simplifying the answer
At the end, the top and bottom are divided by their greatest common factor. 30/45 shares a factor of 15, so it becomes 2/3.
Common questions
How do I type a mixed number?
Whole number, a space, then the fraction: 3 1/2.
Can I use negative fractions?
Yes. Put a minus sign in front, such as -2/5.
Why does dividing by a fraction give a bigger number?
Asking how many halves fit into 3 gives 6. Dividing by something smaller than 1 always increases the result.
Does it show a decimal too?
Yes, along with the percent.