Learn how to find the common factors and the greatest common factor between two numbers!

1. Common Factors and Greatest Common Factor Mrs. Young EMC 1

4. Step 2: Find the factors that are in both lists 40: 1, 2, 4, 5, 8, 10, 20, 40 45: 1, 3, 5, 9, 15, 45 So, the common factors of 40 and 45 are 1 and 5.

5. Step 3: 40: 1 , 2, 4, 5 , 8, 10, 20, 40 45: 1 , 3, 5 , 9, 15, 45 We know that 1 and 5 are common factors, but the greatest common factor is the common factor with the highest value. Compare the common factors to find the greatest common factor (GCF). So, the greatest common factor (GCF) of 40 and 45 is 5. Note that there will only be ONE greatest common factor, but there may be multiple common factors.

7. Step 2: Find the factors that are in both lists 13: 1, 13 15: 1, 3, 5, 15 So, the common factor of 13 and 15 is 1.

8. Step 3: Compare the common factors to find the greatest common factor (GCF). 13: 1 , 13 15: 1 , 3, 5, 15 We know that 1 is the only common factor. So, the greatest common factor (GCF) of 13 and 15 is 1. Note that there will only be ONE greatest common factor, but there may be multiple common factors.

10. Step 2: Find the factors that are in both lists 18: 1, 2, 3, 6, 9, 18 24: 1, 2, 3, 4, 6, 8, 12, 24 So, the common factors of 18 and 24 are 1, 2, 3, and 6

11. Step 3: Compare the common factors to find the greatest common factor (GCF). 18: 1 , 2 , 3 , 6 , 9, 18 24: 1 , 2 , 3 , 4, 6 , 8, 12, 24 We know that 1, 2, 3, and 6 are the common factors, but the greatest common factor is the factor with the greatest value. So, the greatest common factor (GCF) of 18 and 24 is 6. Note that there will only be ONE greatest common factor, but there may be multiple common factors.