List the factors for 8 and List the factors of 12, then list the Greatest Common Factor of 8 and 12

The factors of 8 are: 1, 2, 4, 8.

The factors of 12 are: 1, 2, 3, 4, 6, 12.

The common factors of 8 and 12 are: 1, 2, 4.

Therefore, the Greatest Common Factor of 8 and 12 is 4.