LCM & GCF Calculator
Find the least common multiple (LCM) and greatest common factor (GCF/GCD) of two or more whole numbers, with their prime factorizations.
How to use
- 1Enter two or more whole numbers separated by commas.
- 2Read the GCF, LCM and each number's prime factors.
How it's calculated
GCF by Euclid's algorithm: gcd(a, b) = gcd(b, a mod b). LCM(a, b) = |a × b| ÷ gcd(a, b), applied across the list.
Frequently asked questions
What's the LCM used for?
Adding fractions (the least common denominator), and scheduling problems like 'when do two repeating events line up again'.
What's the GCF used for?
Simplifying fractions and splitting things into the largest equal groups.
Is GCF the same as GCD and HCF?
Yes — greatest common factor, greatest common divisor and highest common factor are the same thing.