static void Main(string[] args) { Animal animal = new Animal(); Duck duck = new Duck(); duck.nNumbOfLegs = 2; BigInteger a = 1; BigInteger b = 1; BigInteger answer = 0; for(BigInteger x = 0; x<40000; x++) { BigInteger y = Fib(a,b); b = a; a = y; answer += y; } Console.WriteLine(answer); Console.Write(duck.nNumbOfLegs); //outputs the number of legs my duck has Console.Read(); //waits for input to keep the console up until keep pressed }