What is the Greatest Common Factor of 12 and 21?

Greatest Common Factor of 12 and 21

Here we will first tell you what the Greatest Common Factor of 12 and 21 is and then show you how we found the Greatest Common Factor of 12 and 21.

The Greatest Common Factor of 12 and 21 is:

3

Step-by-step instructions for how to find the Greatest Common Factor of 12 and 21:

Step 1) We made a list of all the factors of 12 which are 1, 2, 3, 4, 6, 12.

Step 2) Then, we made a list of all the factors of 21 which are 1, 3, 7, 21.

Step 3) Finally, we compared the lists in Step 1 and Step 2 to find that the largest number they have in common is 3. That means that the Greatest Common Factor of 12 and 21 is 3.

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