1. Goal: Find the greatest common factor of two or more numbers.

2.  Factor: when two or more numbers are multiplied together  Common factor: A whole number that is a factor of two or more whole numbers.  Greatest common factor (GCF): is the largest of the common factors.

3.  You must list all the factors for each number  Then circle the biggest number they have in common

4.  4  6  8  12

5.  10  15  12  16

6.  42  56

7.  Find the prime factorization of each number.  Pair all the common prime factors.  Multiply to find GCF