What is the gcf of 81 and 72?

The greatest common factor (GCF) of two numbers is the largest number that divides evenly into both numbers.

To find the GCF of 81 and 72, we can factorize both numbers: 81 = 3^4 72 = 2^3 * 3^2

Now, we determine the common factors between the two numbers: The common factors are 3^2 = 9

Therefore, the GCF of 81 and 72 is 9.