GCF and LCM of 9 and 15
The greatest common factor and least common multiple of 9 and 15.
GCF of 9 and 15
3
LCM of 9 and 15
45
How it works
Break each number into its prime factors:
- 9 = 3²
- 15 = 3 × 5
The GCF (3) multiplies the primes both share, at the lowest power each appears. The LCM (45) multiplies every prime that appears in either number, at the highest power — which is also 9 × 15 ÷ 3 = 45.
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Frequently asked questions
What is the GCF of 9 and 15?+
The greatest common factor (GCF) of 9 and 15 is 3 — the largest number that divides both 9 and 15 with no remainder.
What is the LCM of 9 and 15?+
The least common multiple (LCM) of 9 and 15 is 45 — the smallest number that both 9 and 15 divide into. It equals 9 × 15 ÷ GCF = 135 ÷ 3 = 45.