TrailingZerosInNFactorial.cs

public int TrailingZerosInNFactorial(int n)
{
     var factorialCalulation = calculateFactorial(n);
     var trailingZerosInFactorial = getTrailingZeros(factorialCalculation);

     return trailingZerosInFactorial;
}

private int calculateFactorial(int n)
{
     var initialValue = n; // store the initial value, so we can manipulate n
     var finalValue = 1; // start with nothing

     for (int i = 0; i < initialValue; i++)
     {
           finalValue = finalValue * n; 
           n--;
     }
}

private int getTrailingZeros(int n)
{
     var baseTen = 10;

     var zeroCount = default(int); // start with nothing

     while (n % baseTen == 0)
     {
          n /= baseTen;

          zeroCount++;
     }

     return zeroCount;
}