About Common Denominator Calculator
The least common denominator (LCD) is the smallest number that every denominator in a set of fractions divides into evenly. This calculator first reduces each fraction to lowest terms, then takes the least common multiple of the denominators, using LCM(a, b) = |a × b| ÷ GCD(a, b). Each fraction is rewritten by multiplying its numerator by LCD ÷ denominator. Separate fractions with commas or new lines.
How to use Common Denominator Calculator
- Type or paste into the "Fractions (one per line or separated by commas)" box, or press "Use example" to try it with sample data.
- The result appears below and updates as you type.
- Copy the result with the copy button, or download it as a file where that is offered.
Questions about Common Denominator Calculator
Why do I need a common denominator?
Fractions can only be added, subtracted, or compared directly when they count the same size of part. Rewriting 1/2 and 2/3 as 3/6 and 4/6 makes the comparison and the sum straightforward.
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