Basic Programs useful for interviews

1) Write a program to find Factorial of a number in C#?
class Factorial
{ private static int temp = 1;
public static int CalFactorial(int n)

{ temp = temp * n;

   return temp;
}
static void Main(string[] args)
{
Console.WriteLine("Enter A Number:");
int fact = Convert.ToInt32(Console.ReadLine());
int x = 1;
for (int i = 1; i <= fact; i++)
{
x = Factorial.CalFactorial(i);
}
System.Console.WriteLine(x);
Console.ReadLine();
  }
}