To add or subtract fractions, give them a common denominator first; to multiply, multiply across; to divide, flip the second fraction and multiply. 1/2 + 1/3 = 5/6. Enter two fractions and the operation; the calculator simplifies the answer, gives it as a mixed number and a decimal, and lists each step so you can follow or check homework.
The four operations
| Operation | Rule | Example |
|---|---|---|
| Add | a/b + c/d = (ad + cb) / bd | 1/2 + 1/3 = (3 + 2)/6 = 5/6 |
| Subtract | a/b − c/d = (ad − cb) / bd | 3/4 − 1/3 = (9 − 4)/12 = 5/12 |
| Multiply | a/b × c/d = ac / bd | 2/3 × 3/4 = 6/12 = 1/2 |
| Divide | a/b ÷ c/d = ad / bc | 3/4 ÷ 3/8 = 24/12 = 2 |
Multiplying the two denominators always gives a common denominator, though not always the smallest one. The calculator then simplifies the result, so you get the same answer either way.
Fractions, decimals and percentages
| Fraction | Decimal | Percent |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.3333… | 33.33% |
| 2/3 | 0.6667… | 66.67% |
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
| 1/5 | 0.2 | 20% |
| 1/6 | 0.1667… | 16.67% |
| 1/8 | 0.125 | 12.5% |
| 3/8 | 0.375 | 37.5% |
| 5/8 | 0.625 | 62.5% |
| 7/8 | 0.875 | 87.5% |
| 1/10 | 0.1 | 10% |
| 1/12 | 0.0833… | 8.33% |
| 1/16 | 0.0625 | 6.25% |
Fractions whose denominator has only 2s and 5s as factors (halves, quarters, eighths, fifths, tenths) give decimals that end; all others repeat forever, like 1/3 = 0.333…
Mixed numbers
An improper fraction such as 11/4 is “2 and 3/4”: divide 11 by 4 to get 2, with 3 left over. To go back, multiply the whole number by the denominator and add the numerator: 2 × 4 + 3 = 11, so 11/4. To add mixed numbers, convert them to improper fractions first.
Where fractions still matter
Recipes (¾ cup), US tape measures (5/8 inch), music (3/4 time), betting odds (5/2) and probability (1 in 6) all use fractions. A fraction keeps exact values that a decimal would round: 1/3 stays exactly a third.
Once zet4u is saved on your device, the calculator works offline, so it is there for homework or a workshop without Wi-Fi.
Frequently asked questions
How do I add fractions with different denominators?
Give them a common denominator, then add the numerators. 1/2 + 1/3: the common denominator is 6, so 3/6 + 2/6 = 5/6.
How do I multiply fractions?
Multiply the numerators together and the denominators together, then simplify. 2/3 × 3/4 = 6/12 = 1/2.
How do I divide fractions?
Flip the second fraction and multiply. 3/4 ÷ 3/8 = 3/4 × 8/3 = 24/12 = 2.
How do I simplify a fraction?
Divide the top and the bottom by their greatest common divisor. 18/24: both divide by 6, giving 3/4.
How do I turn a fraction into a percentage?
Divide the numerator by the denominator and multiply by 100. 3/8 = 0.375 = 37.5%.
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