GCF and LCM of 6 and 15
The greatest common factor and least common multiple of 6 and 15.
GCF of 6 and 15
3
LCM of 6 and 15
30
How it works
Break each number into its prime factors:
- 6 = 2 × 3
- 15 = 3 × 5
The GCF (3) multiplies the primes both share, at the lowest power each appears. The LCM (30) multiplies every prime that appears in either number, at the highest power — which is also 6 × 15 ÷ 3 = 30.
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Frequently asked questions
What is the GCF of 6 and 15?+
The greatest common factor (GCF) of 6 and 15 is 3 — the largest number that divides both 6 and 15 with no remainder.
What is the LCM of 6 and 15?+
The least common multiple (LCM) of 6 and 15 is 30 — the smallest number that both 6 and 15 divide into. It equals 6 × 15 ÷ GCF = 90 ÷ 3 = 30.