Console.WriteLine("Please Choose an option from the menu!");
Console.WriteLine("If you would like to calculate n!, please press 1. ");
Console.WriteLine("If you would like to calculate nPr, please press 2. ");
int choice = int.Parse(Console.ReadLine());
Console.WriteLine("Please enter your value");
long ans = long.Parse(Console.ReadLine());
Console.WriteLine("The Factorial of " + ans + "= " + Fact(ans));
Console.WriteLine("Please enter your first value");
long num1 = long.Parse(Console.ReadLine());
Console.WriteLine("Please enter your second value");
long num2 = long.Parse(Console.ReadLine());
Console.WriteLine(num1+ "P" + num2 + "= " + nPr(num1, num2));
{Console.WriteLine("Please Enter a Valid Choice");
static public long Fact(long a)
for(int i = 1; i <= a; i++)
static public long nPr(long n, long r)
{ long perm = Fact(n) / Fact(n - r);