GCF & LCM Calculator
Enter two or more integers to find their greatest common factor (GCF) and least common multiple (LCM).
Positive integers, comma or space separated.
- GCF6
- LCM72
How it works
GCF via Euclid's algorithm. LCM(a, b) = |a·b| / GCF(a, b).
GCF(12, 18) = 6. LCM(12, 18) = 36.
Frequently asked questions
- Is GCF the same as HCF?
- Yes — GCF and HCF (highest common factor) are identical.
- Why is LCM useful?
- Adding fractions requires a common denominator — the LCM of the denominators.
- Do negatives matter?
- Sign is ignored — GCF and LCM are defined as non-negative.
- More than two numbers?
- Yes — apply GCF/LCM pairwise across the list.
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