What is the gcf of 10 and 15?

The GCF (Greatest Common Factor) of 10 and 15 is 5. This is the largest number that both 10 and 15 can be divided by evenly without any remainder. The factor pairs of 10 are (1, 10) and (2, 5), while the factor pairs of 15 are (1, 15) and (3, 5). The common factor(s) of 10 and 15 are the numbers that appear in both lists, which in this case is only 5.