Hi.
The divisibility rule of 3 states that if the sum of the digits in the number add up to a multiple of 3, it is divisible by 3.
To put it in simpler words, to find out if 81 is a multiple of 3 we must add 8 & 1.
8 + 1 = 9
9 is a multiple of 3 (3 • 3 = 9).
81 is a multiple of 3.
I hope I helped you understand!
