Fraction calculator
Math & numbersHow much is that in fractions?
Add, subtract, multiply and divide fractions and mixed numbers, or turn a decimal into a fraction, with the answer in lowest terms.
What you enter stays on your device while you use this tool. Opening a shared link sends the settings in its address to HowToolbox to prepare the page.
Answer in lowest terms
9/4
1 1/2 + 3/4 = 9/4
The same answer
- Mixed number
- 2 1/4
- Decimal
- 2.25
- Working
- 3/2 + 3/4 = (3×4 + 3×2) / (2×4) = 18/8 = 9/4
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Add, subtract, multiply and divide fractions and mixed numbers, or turn a decimal into a fraction, with the answer in lowest terms.
How to use
- Type the first number, choose add, subtract, multiply or divide, and type the second. Write 3/4 for a fraction, 1 3/4 for a mixed number.
- To turn a decimal into a fraction, switch to Decimal to fraction and type the decimal.
- Copy the answer in the form you need, or copy the link to share the same calculation.
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How it works
A fraction a/b is a parts out of b equal parts of a whole. To add or subtract, the parts must be the same size, so a/b ± c/d = (a×d ± c×b) / (b×d). To multiply, multiply the tops and the bottoms: a/b × c/d = (a×c) / (b×d). To divide, multiply by the upside-down fraction: a/b ÷ c/d = (a×d) / (b×c).
The result is shown in lowest terms: top and bottom are divided by their greatest common divisor, so 10/8 becomes 5/4. A mixed number such as 2 1/4 is a whole number plus a proper fraction, and 5/4 is the same amount as 1 1/4. For example, 1 1/2 + 3/4 is 3/2 + 3/4 = (3×4 + 3×2) / (2×4) = 18/8 = 9/4 = 2 1/4.
A decimal is a fraction with a denominator of 10, 100, 1000 and so on: 0.375 is 375/1000 = 3/8. Many fractions have decimals that never end but repeat; 1/3 is 0.333… and 7/12 is 0.58333…, written here as 0.(3) and 0.58(3), with the repeating digits in parentheses. All arithmetic is exact, so there is no rounding in the fraction.
Worked example
What is 2/3 multiplied by 3/4?
- Multiply the numerators and denominators, then simplify: 2/3 × 3/4 = (2×3) / (3×4) = 6/12 = 1/2.
The fraction in lowest terms is 1/2.
Frequently asked questions
How do I add fractions with different denominators?
Give them a common denominator first. 1/2 + 1/3 = 3/6 + 2/6 = 5/6. The working line shows each step.
How do I write a mixed number?
Type the whole number, a space and the fraction: 2 1/4 means two and a quarter. A minus sign in front makes the whole number negative.
Why is dividing by a fraction the same as multiplying by its flip?
Dividing by 1/4 asks how many quarters fit, and each whole has four, so you multiply by 4. In general a ÷ (c/d) = a × (d/c).
Can I use a decimal as one of the numbers?
Not in the arithmetic. First turn it into a fraction with Decimal to fraction, then use that fraction. A fraction with 0 on the bottom or a division by zero is refused.
Can I type a repeating decimal such as 0.(3)?
No. Decimal input accepts terminating decimals only. Enter 1/3 in fraction mode for an exact third; 0.333 is a different, terminating value.
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