c# program

Like many problems of this type, this one can be solved in one line using LINQ, the answer being 192:

  int numZero = Enumerable.Range(1, 1000).Sum(n => n.ToString().Count(c => c == '0'));

Although this isn't the most efficient way to do it, the logic is to:

1. Convert each number between 1 and 1000 to a string

2. Count how many characters are '0' in this string.

3. Sum the results of  step 2.

Assuming you're not allowed to use LINQ, I'd reproduce this logic using traditional code.