How to add and subtract fractions
Fractions need the same denominator (bottom number) before you can add or subtract them. The quick method is to cross-multiply: a/b + c/d = (a×d + c×b) / (b×d). Then simplify. Example: 1/2 + 1/3 = (3 + 2) / 6 = 5/6. For subtraction, use a minus in the middle: 3/4 − 1/6 = (18 − 4) / 24 = 14/24 = 7/12.
How to multiply and divide fractions
To multiply, multiply the tops together and the bottoms together: 2/3 × 3/5 = 6/15 = 2/5. To divide, flip the second fraction and multiply ("keep, change, flip"): 3/4 ÷ 1/8 = 3/4 × 8/1 = 24/4 = 6.
Simplifying
A fraction is in its simplest form when the top and bottom have no common factor except 1. The calculator divides both by their highest common factor using Euclid's algorithm, so 14/24 becomes 7/12. Negative answers keep the minus sign on the top.
Mixed numbers and decimals
An improper fraction such as 7/4 is shown as the mixed number 1 3/4: 7 ÷ 4 = 1 remainder 3. To enter a mixed number, convert it first: 2 1/3 = (2×3 + 1)/3 = 7/3. Decimals are rounded to 6 places, so 1/3 shows as 0.333333.
Who it's for
Useful for KS2, KS3 and GCSE maths homework, checking recipe and DIY measurements, or splitting bills. The working appears under every answer so students can see the method, not just the result. For percentages, use the percentage calculator.
Frequently asked questions
How do you add fractions with different denominators?
Cross-multiply: a/b + c/d = (ad + cb)/bd, then simplify. 1/2 + 1/3 = 5/6.
How do you divide fractions?
Flip the second fraction and multiply. 3/4 ÷ 1/8 = 3/4 × 8 = 6.
How do I enter a whole number?
Put it over 1, for example 3/1.
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