Question

If 1x35 is divisible by 9, then find the posible value (s) of x.

Answer 1

If 1x35 is divisible by 9, then the sum of its digits is also divisible by 9.
i.e. 1 + x + 3 + 5 is divisible by 9.
$\Rightarrow$ 9 + x can take values 0, 9, 18, 27, .....
$\Rightarrow$ 9 + x = 9 or 18
$\Rightarrow$ x = 0 or 9
The possible values of x are 0 and 9.