In this Section:
In this section, we introduce the concept of a common factor. Recall that in multiplication, the numbers multiplied together are called factors. When two or more numbers share a factor, that factor is said to be a “common factor”. The greatest common factor (GCF) is the largest factor for a group of numbers. This is easily found by factoring all of the numbers in the group and finding what is common to each. We also clear up a common point of confusion. If a number is a factor of another, it’s also a divisor. For example, four is a factor of twelve, since four times three is twelve. Four is also a divisor of twelve for the same reason. Twelve divided by four is three. Therefore if we find the GCF, we have also found the GCD or greatest common divisor. These two often get mixed up at first and it’s important to understand that they are the same.