public static void Main()
Console.WriteLine(Add(4, 8));
Console.WriteLine(sub(4, 8));
Console.WriteLine(mult(4, 8));
Console.WriteLine(div(4, 2));
static int Add(int num1, int num2)
static int sub(int num1, int num2)
static int mult(int num1, int num2)
static int div(int num1, int num2)