GCF and LCM of 16 and 20
The greatest common factor and least common multiple of 16 and 20.
GCF of 16 and 20
4
LCM of 16 and 20
80
How it works
Break each number into its prime factors:
- 16 = 2⁴
- 20 = 2² × 5
The GCF (4) multiplies the primes both share, at the lowest power each appears. The LCM (80) multiplies every prime that appears in either number, at the highest power — which is also 16 × 20 ÷ 4 = 80.
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Frequently asked questions
What is the GCF of 16 and 20?+
The greatest common factor (GCF) of 16 and 20 is 4 — the largest number that divides both 16 and 20 with no remainder.
What is the LCM of 16 and 20?+
The least common multiple (LCM) of 16 and 20 is 80 — the smallest number that both 16 and 20 divide into. It equals 16 × 20 ÷ GCF = 320 ÷ 4 = 80.