Add fractions with different bottom numbers
3/4 + 2/3 = (3 × 3 + 2 × 4) / 12 = 17/12, which is also 1 5/12.
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Fraction calculator
Add, subtract, multiply, or divide two fractions and get the simplest answer.
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Formula and steps included
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Optional learning Learn how this math works See the formula, definitions, and step-by-step method.
Formula
How fraction operations work
Add or subtract: a/b ± c/d = (ad ± bc) / bd; Multiply: a/b × c/d = ac / bd; Divide: a/b ÷ c/d = ad / bc
Addition and subtraction need a common denominator because the parts must have the same size. Cross-multiplying creates an equivalent common-denominator form.
Multiplication works straight across. For division, flip the second fraction (this flipped fraction is called its reciprocal), then multiply. Finish by making the answer as small as possible.
How to use the formula
Enter the fractions and choose the math sign
Type both top and bottom numbers. A bottom number cannot be zero because dividing by zero is not allowed.
Apply the matching formula
Make matching bottom numbers for addition or subtraction, multiply straight across, or flip the second fraction before division.
Simplify the result
Divide the numerator and denominator by their greatest common factor and convert to a mixed number if that format is useful.
Worked examples
Fraction calculator examples
Divide and simplify
5/6 ÷ 10/9 = 5/6 × 9/10 = 45/60 = 3/4.
Common questions
Fraction calculator FAQ
Can the fraction calculator handle improper fractions?
Yes. An improper fraction is calculated the same way as any other fraction, and the simplified result can also be expressed as a mixed number.
Why can a denominator not be zero?
A fraction represents division by its denominator. Division by zero has no defined numeric result, so every denominator must be nonzero.
How is a fraction simplified?
Find the greatest common factor of the numerator and denominator, then divide both by that factor. Their ratio stays the same.
Are my fractions sent anywhere?
Your fractions stay in your browser and are not saved by default or uploaded. Use Save on this device to keep them here, or download a backup file.