What is the divisibility rule for 27?

Subtract 8 times the last digit from remaining truncated number. Repeat the step as necessary. If the absolute of result is divisible by 27, the original number is also divisible by 27

Check for 945:

94-(8*5)=54;

5-(8*4)=-27

Since 27 is divisible by 27, the original no. 945 is also divisible.

Check for 264681:

26468-(8*1)=26460;

2646-(8*8)=2582;

264-(8*6)=216

21-(8*6)=-27

Since 27 is divisible by 27, the original no. 264681 is also divisible.

Check for 81:

8-(8*1)=0;

Since 0 is divisible by 27, the original no. 81 is also divisible.