Greatest Common Factor Worksheet and Solutions

Objective: I can find the greatest common factor.

One way to find the greatest common factor (GCF) is

Step 1: List the factors of two numbers.

Step 2: Find the factors common to both numbers.

Step 3: Select the greatest common factor.

Read the lesson on greatest common factor if you need to learn how to find the greatest common factor.

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Find the GCF of the following:

6, 9

8, 12

6, 20

12, 15

15, 18

18, 27

9, 15

8, 10

12, 18

9, 12

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