Question

A number is formed by writing the same digit 8 times.The number is always divisible by
1) 7
2) 13
3) 19
4) None of these

Answer 1

Easiest way to do this is check every number that follows that pattern and see if it fails any of them. For example, 11111111 / 7 fails. That means 1 is wrong.

Test each one of these until a number works on 1 - 9 all 8 times, or until each number fails at least once.

Answer 2

* When I say that "1 is wrong", I'm saying choice 1 (7) is not the right answer. So try 2 (dividing by 13). And so on.