Answer:
8
Explanation:
The Greatest Common Factor of two numbers is the largest whole number that goes into both of them. To find it, we can lay out all the factors of each number and pick the largest one.
Factors of 16: 1, 2, 4, 8, 16
Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
The largest number that shows up on both lists of factors is 8, so the GCF of 16 and 72 is 8.