How can I do math inside methods in C#?

Why is it that when I call this method:


public double Combinations(int n, int k)


{


return (double)(Factorial(n) / (Factorial(k) * Factorial(n - k)));


}





I get an output of 3 different integers. I get the correct integers but I want them to be divided, added and subtracted like the math says above and therefore get a single answer (according to the math above). Why doesn't it do that?? I'm calling it from a different method :





public static void Main()


{


MegaMillionsOdds megaMillions = new MegaMillionsOdds();


megaMillions.Combinations(5,4);


}

How can I do math inside methods in C#?
You're doing integer division and therefore losing accuracy (1/3=0). You need to cast the output of the Factorial function to a double, and then do the division.





double a = Factorial(n);


double b = Factorial(k) * Factorial(n - k);


return a / b;