GCF and LCM of 8 and 18
The greatest common factor and least common multiple of 8 and 18.
GCF of 8 and 18
2
LCM of 8 and 18
72
How it works
Break each number into its prime factors:
- 8 = 2³
- 18 = 2 × 3²
The GCF (2) multiplies the primes both share, at the lowest power each appears. The LCM (72) multiplies every prime that appears in either number, at the highest power — which is also 8 × 18 ÷ 2 = 72.
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Frequently asked questions
What is the GCF of 8 and 18?+
The greatest common factor (GCF) of 8 and 18 is 2 — the largest number that divides both 8 and 18 with no remainder.
What is the LCM of 8 and 18?+
The least common multiple (LCM) of 8 and 18 is 72 — the smallest number that both 8 and 18 divide into. It equals 8 × 18 ÷ GCF = 144 ÷ 2 = 72.