/// <summary>
/// Run solution for problem 20.
/// </summary>
/// <param name="factorialInput">Factorial input.</param>
/// <returns>Sum of factorial result's digits.</returns>
public static int Run(int factorialInput)
{
return(LargeNumberMath.GetFactorial(factorialInput).ToCharArray().Aggregate(0, (sum, digit) =>
{
return sum + int.Parse(digit.ToString());
}));
}
public void GetFactorial_Returns_Factorial_Result()
{
var number = 10;
var expected = Enumerable.Range(1, number).Aggregate(1, (factorial, number) => factorial * number);
LargeNumberMath.GetFactorial(number).Should().Be(expected.ToString());
}