This GCF calculator finds the greatest common factor of 2, 3 or 4 numbers which in math is also known as the greatest common divisor (GCD).

## What does GCF stand for?

In mathematics, GCF is the abbreviation for the Greatest Common Factor which represents the largest positive integer that divides without a remainder two or more given numbers. It represents the same as the greatest common divisor (GCD).

In regard of how to find it, let us take two examples and explain it in detail:

Example 1: find the GCF for 24 and 36.

First move is to find the prime factors of each of the 2 number by applying the prime factorization rule:

25 = 5 * 5

45 = 3 * 3 * 5

Second step is to find those prime factors that both figures have in common, and multiply them. In our case only 5 is a common factor thus the GCF = 5.

Example 2: calculate the GCF for 42 and 63.

First step is the prime factorization:

42 = 2 * 3 * 7

63 = 3 * 3 * 7

Second step is to check what factors have these 2 numbers in common: in this case 3 and 7. Then multiply them and get a GCF = 21.

If in case of easy numbers finding them this value by hand may by facile in case of more complex numbers or when the numbers to be taken into account exceeds two you can use this GCF calculator that allows you to find it for up to 4 numbers at a time.

13 Apr, 2015