06.LoopsHomework/07.CalculateCombinatoric

//Problem 7.    Calculate N! / (K! * (N-K)!)
//In combinatorics, the number of ways to choose k different members out of a group of n different elements (also known as the number of combinations) is calculated by the following formula:
//For example, there are 2598960 ways to withdraw 5 cards out of a standard deck of 52 cards. Your task is to write a program that calculates n! / (k! * (n-k)!) for given n and k (1 < k < n < 100). Try to use only two loops.

using System;
using System.Numerics;

class CalculateCombinatoric
{
    static BigInteger FactorialCalc(uint number)
    {
        BigInteger sum = 1;
        for (int i = 1; i <= number; i++)
        {
            sum = sum * i;
        }
        return sum;
    }

    static void Main()
    {
        Console.WriteLine("Calculate   N!/(K!*(N-K)!");
        Console.Write("Enter N:");
        uint n = uint.Parse(Console.ReadLine());
        Console.Write("Enter K:");
        uint k = uint.Parse(Console.ReadLine());
        BigInteger result = FactorialCalc(n) / ((FactorialCalc(k) * FactorialCalc(n - k)));
        Console.Write("The Result is:{0}",result);
        Console.WriteLine();
    }
}