Question

if a mobile has 5 digits password then how many different password s can be set so that it must be divisible by 4

Answer 1

The first digit can be from 1 to 9.
2nd , 3rd digits can be any from  0 to 9.
4th and fifth digits must be one of  04, 08, 12, 16, 20, ...96, 00.
    => 25 possibilities.

Total combinations and permutations:    9 * 10 * 10 * 25
   = 22,500.