Is 534 divisible by 9?
No.
To test: add the digits together and if the sum is divisible by
9, so is the original number.
The test can be repeated on the sum until a single digit
remains.
If this single digit is 9 then the [original] number is
divisible by 9, otherwise it gives the remainder when the
[original] number is divided by 9.
534 → 5 + 3 + 4 = 12
12 → 1 + 2 = 3
3 ≠ 0 so 12 is not divisible by 9 so 534 is not divisible by 9;
the remainder when 534 is divided by 9 is 3.