GCF and LCM of 4 and 5
The greatest common factor and least common multiple of 4 and 5.
GCF of 4 and 5
1
LCM of 4 and 5
20
How it works
Break each number into its prime factors:
- 4 = 2²
- 5 = 5
The GCF (1) multiplies the primes both share, at the lowest power each appears. The LCM (20) multiplies every prime that appears in either number, at the highest power — which is also 4 × 5 ÷ 1 = 20.
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Frequently asked questions
What is the GCF of 4 and 5?+
The greatest common factor (GCF) of 4 and 5 is 1 — the largest number that divides both 4 and 5 with no remainder.
What is the LCM of 4 and 5?+
The least common multiple (LCM) of 4 and 5 is 20 — the smallest number that both 4 and 5 divide into. It equals 4 × 5 ÷ GCF = 20 ÷ 1 = 20.