To find the factors of the number 72 you will have to find the two numbers which give a product of 72. This means that when you multiply 2 numbers they will give a product of 72.
So let us start with the process:
1×72=72
2×36=72
3×24=72
4×18=72
6x 12=72
8x 9 = 72
So you can see that the factors of 72 are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36 and 72.