Find the Greatest Common Factor (GCF / GCD) and Least Common Multiple (LCM) of two or more integers — with prime factorisation working shown step by step.
Enter Numbers
GCF (Greatest Common Factor)
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LCM
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GCF / GCD
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LCM
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GCF × LCM
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Count
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numbers
Enter at least two numbers
GCF = largest number dividing all. LCM = smallest multiple of all.
Frequently Asked Questions
What is GCF (GCD)?
GCF (Greatest Common Factor) — also called GCD — is the largest positive integer that divides all given numbers without a remainder. Used to simplify fractions: GCF(12,18) = 6.
What is LCM?
LCM (Least Common Multiple) is the smallest positive integer that all given numbers divide into exactly. Used for adding fractions with different denominators: LCM(4,6) = 12.