What is the gcf of the numbers 68 and 104?

Answer 1

First break each number down into its prime factors:

68 = 2 x 2 x 17

104 = 2 x 2 x 2 x 13

Now look for the factors which occur in both lists, in this case 2 x 2. So the greatest common factors of 68 and 104 is 2 x 2 = 4.