public int trailing0s(int num){
        int pow = 5;
        int count = 0;
        while(pow <= num){
            count += num/pow;
            pow *= 5;
        }
        return count;
    }
150qs hard section
lets consider 625. First we divide 625 by 5 and that takes care of one 5
till 625. Then we divide 625 with 25 and that takes care of numbers with 2
5s. We keep doing this till divisor becomes greater than number.
src/com/interview/number/Trailing0sinFactorial.java