I recently learned how to find the GCF (Greatest Common Factor) of two numbers. The GCF is the highest integer that divides into the two numbers. In order to find it, you need to first find the prime factors of the two numbers, then compare the two groups of prime numbers and look for pairs as illustrated below. Take one number from each pair and multiply it with the other numbers you take from the pairs, the product is the GCF.

How to find the prime factors.

How to find the GCF with the prime numbers.