What Is GCF (Greatest Common Factor)?
GCF stands for greatest common factor, sometimes called GCD (greatest common divisor). It's the largest number that divides evenly into every number in a set, with nothing left over. It's most often used to reduce a fraction to its simplest form.
Example
The GCF of 24 and 36 is 12, since 12 is the largest number that divides evenly into both.