GCF Calculator

Find the greatest common factor (also called the greatest common divisor) of a list of whole numbers.

Separate with commas or spaces.
Whole numbers only.
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GCF
LCM
Prime factorizations
Euclid’s steps (first two numbers)
Work

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How to Find the GCF and LCM

GCF: multiply the prime factors every number shares, at the lowest power
LCM: multiply every prime factor that appears, at the highest power
For two numbers: GCF × LCM = a × b   Euclid: gcd(a, b) = gcd(b, a mod b)

Worked Example

Tips

Use the GCF to simplify fractions (24/36 ÷ 12 = 2/3) and the LCM to find a common denominator (1/24 + 1/36 uses 72).