GCF and LCM of 40 and 100
The greatest common factor and least common multiple of 40 and 100.
GCF of 40 and 100
20
LCM of 40 and 100
200
How it works
Break each number into its prime factors:
- 40 = 2³ × 5
- 100 = 2² × 5²
The GCF (20) multiplies the primes both share, at the lowest power each appears. The LCM (200) multiplies every prime that appears in either number, at the highest power — which is also 40 × 100 ÷ 20 = 200.
Try other numbers
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Frequently asked questions
What is the GCF of 40 and 100?+
The greatest common factor (GCF) of 40 and 100 is 20 — the largest number that divides both 40 and 100 with no remainder.
What is the LCM of 40 and 100?+
The least common multiple (LCM) of 40 and 100 is 200 — the smallest number that both 40 and 100 divide into. It equals 40 × 100 ÷ GCF = 4000 ÷ 20 = 200.