Factors, Common Factors, and GCF

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

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.

Vocabulary

You must list all the factors for each number

Then circle the biggest number they have in common

Finding factors, Common Factors, and GCF:

Find the factors, common factors, and GCF of … 4

6

8

12

Find the factors, common factors, and GCF of … 10

15

12

16

Find the factors, common factors, and GCF of … 42

56

Find the prime factorization of each number.

Pair all the common prime factors. Multiply to find GCF

Find GCF using Prime Factorization: better for bigger numbers

Find the GCF of 9 and 12

Find the GCF of 20 and 24

Find the GCF of 54 and 60

Find the GCF of 72 and 48