using System;

using System.Linq; 

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var e = NumMethods.GetFizzBuzz(400);

        foreach (var i in e)

        {

            Console.WriteLine(i);

        }

    }

}

​

public static class NumMethods

{

    public static IEnumerable<string> GetFizzBuzz(int max)

    {

        int current = 0;

        while (current<max)

        {

            current += 1;

            bool isFizz = (current % 3 == 0);

            bool isBuzz = (current % 5 == 0);

            if (isFizz && isBuzz)

            {

                yield return "fizzbuzz";

            }

            else if (isFizz)

            {

                yield return "fizz";

            }

            else if (isBuzz)

            {

                yield return "buzz";

            }

            else 

            {

                yield return current.ToString(); 

            }

        }

    }

};