Greatest Common Factor Calculator or formulas

Greatest common factor (GCF) calculator. Is also known as greateset common divisor (GCD).

GCF calculator

First number:
Second number:
Greatest common factor (gcf):
Least common multiple (lcm):

What is the Greatest Common Factor and how calculate with formulas

The greatest common factor (GCF or GCD or HCF) of a set of whole numbers is the largest positive integer that divides evenly into all numbers with zero remainder. For example, for the set of numbers 18, 30 and 42 the GCF = 6.

GCF example

Find GCF for numbers 8 and 12:

The divisors of 8 are:

8 = 2×2×2

The divisors of 12 are:

12 = 2×2×3

So the common divisors of 8 and 12 are:

gcf = 2×2 = 4

So 8/12 fraction, can be reduced to 2/3:

8 / 12 = (8/4) / (12/4) = 2 / 3