The GCF of 8, 36, and 12 is 4. To find it:
Write the prime factors of the three numbers:
8 = 2 × 2 × 2 = 2³;
36 = 2 × 2 × 3 × 3 = 2² × 3³; and
12 = 2 × 2 × 3 = 2² × 3.
Find the factors that repeat in both factorizations. In this case, we have only 2².
4 is the greatest common factor as:
8/4 = 2;
36/4 = 9; and
12/4 = 3.