Question

How to write in general math terms that a number is not a multiple of 3. Like for instance if I wanted to write that a number is a multiple of 3 I would write a=3k, but now I what to write the opposite of that?

Answer 1

What is the actual math problem?

Answer 2

How to write that a numbers is not a multiple of 3

Answer 3

If a=3k is a multiple of 3, how do i write that a is not a multiple e of 3

Answer 4

If sum of digits in a number is multiple of 3 then number is multiple of 3 e.g., for 612 sum of digits is 9 so it’s a multiple of 3. But this solution is not efficient. You have to get all decimal digits one by one, add them and then check if sum is multiple of 3.

There is a pattern in binary representation of the number that can be used to find if number is a multiple of 3. If difference between count of odd set bits (Bits set at odd positions) and even set bits is multiple of 3 then it is the number.