This document discusses finding the greatest common factor (GCF) of two numbers. It defines factors as numbers that are multiplied to get a product, and common factors as factors shared between two numbers. The greatest common factor is the largest of the common factors. The document then describes three methods for finding the GCF: 1) listing all factors and identifying the greatest common, 2) using a factor tree to get the prime factorizations, and 3) continuously dividing the numbers until there is no more common division.