GCF & LCM
Greatest common factor and least common multiple of a set of whole numbers.
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The formula
GCF via the Euclidean algorithm; LCM = a × b ÷ GCF
The greatest common factor is the largest number dividing everything evenly; the least common multiple is the smallest number they all divide into. GCF simplifies fractions and ratios, LCM finds common denominators and works out when repeating cycles line up again.
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Common questions this calculator answers — select one to load its values.
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Frequently asked questions
What are the GCF and LCM used for?+
The GCF simplifies fractions and ratios; the LCM finds common denominators and synchronises repeating cycles.
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