add up the digits that make 81 as follows: 8 + 1 = 9
We know that if the sum of the numbers that make up 81 is divisible by 3, then 81 is divisible by 3.
Since the sum of the digits in 81 is divisible by 3, 81 is also divisible by 3. Thus, the answer to the question "Is 81 divisible by 3?" is as follows:
Yes
