public static void Main()
{
var factorialString = Permutation.CalculateFactorial(100).ToString();
var sum = 0;
for (var i = 0; i < factorialString.Length; i++)
{
sum += int.Parse(factorialString[i].ToString());
}
Console.WriteLine($"Sum of digits for 100 factorial: {sum}");
Console.ReadKey();
}
public void WhenNegativeInput_ThenCalculatingFactorialThrowsError()
{
Permutation.CalculateFactorial(-234);
}