To find the greatest Common factor of two numbers you must first find all of the factors of each given number. For example:

Find the Greatest Common Factor of **8 and 24**.

**1. Find all of the factors of 8**

8×1=8

2×4=8

So, the factors of 8 are: 1,2,4,8 (the numbers that when multiplied together give you a product which equals the number you are working with)

**2. Find the factors of 24**.

1×24=24

2×12=24

3×8=24

4×6=24

So, the *factors of 24* are: 1,2,3,4,6,8,12,24

The common* factors of 8* and 24 are 1,2,4,8

The Greatest Common Factor (GCF) of 8 and 24 is** 8**

You can also find the GCF of two or more numbers **using a factor tree.**

Example: Find the GCF of 8 and 24 using a factor tree:

## Practice