using System;

public class Program

{

    float CalculoFactorial ( int x )

    {

        float r = 1;

        for ( int i = 1; i <= x; i ++)

        {

            r = r * i;

        }

        return r;

    }

    public void Main()

    {

        int n = 5;

        int r = 3;

        float f1 = 0; // Almacena factorial numerador

        float f2 = 0; // Almacena factorial denominador

        float res=0;

        f1 = CalculoFactorial ( n );

        f2 = CalculoFactorial ( n-r );

        res = f1/f2;

        Console.WriteLine( res );

}

​

    }

​