Find the smallest nonzero number that is divisible by both 6 and 9.

First, let’s write down a few of the smallest numbers that are completely divisible by 6.
6 * 1 = 6
6 * 2 = 12
6 * 3 = 18
6 * 4 = 24
6 * 5 = 35, etc.
Further, among these numbers we find a number that is divisible by 9 without a remainder:
6/9 = 0.6 …. not divisible.
12/9 = 1.33 … not divisible.
18/9 = 2.
So, the smallest number that is divisible by 6 and 9 completely is 18.
Answer: 18.