Greatest Common Factor

1. Finding the Greatest Common Factor

2. The greatest common factor of two or more numbers is the greatest number that is a factor of every number.

3. There are two methods for finding the GCF. 1. Listing the factors 2. Using the Ladder

4. To find the GCF of two numbers using a list, list the factors of one number. Then list the factors of the second number. The GCF is the greatest value that appears on both lists.

5. 1. Make a list to find the GCF of 18 and 30 18: 1, 2, 3, 6, 9, 18 30: 1, 2, 3, 5, 6, 10, 15, 30 THE GCF of 18 and 30 is 6.

6. To find the GCF of two numbers using the ladder method, determine a prime number that you can divide evenly into each number. Write the number on the side and divide. Continue as far as you can!

7. 27 36 9 12 3 3 3 4 3 x 3 =9 so the GCF is 9 2. Use a ladder to find the GCF of 27 and 36