Loops - Factoriel Equation

using System;

class Program
{
    static void Main(string[] args)
    {
        //Option 1
        bool successParse;
        decimal enteredN, enteredK;
        decimal valueN = 1;
        decimal valueK = 1;
        decimal factorielKMinusN =1;

        do
        {
            Console.Write("Enter N: ");
            decimal.TryParse(Console.ReadLine(), out enteredN);
            Console.Write("Enter K: ");
            successParse = decimal.TryParse(Console.ReadLine(), out enteredK);

            if (enteredK <= enteredN || enteredN <= 1)
            {
                Console.WriteLine("Error!");
                successParse = false;
            }

        } while (!successParse);

        for (int i = 1; i <= enteredN; i++)
        {
            valueN = valueN * i;
        }

        for (int i = 1; i <= enteredK; i++)
        {
            valueK = valueK * i;
        }
        decimal difference = (enteredK - enteredN);
        for (int i = 1; i <= difference; i++)
        {
            factorielKMinusN = factorielKMinusN * i;
        }

        Console.WriteLine("Factoriel !N is: {0}", valueN);
        Console.WriteLine("Factoriel !K is: {0}", valueK);
        Console.WriteLine("Factoriel minus is: {0}", factorielKMinusN);
        Console.WriteLine("The equation (!N*!K)/(K-N) is: {0}", valueN*valueK/factorielKMinusN);

    }
}