using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(FormatSpeed(100.0, 10.0));

        Console.WriteLine(FormatSpeed(1000.0, 10.0));

        Console.WriteLine(FormatSpeed(2000.0, 10.0));

        Console.WriteLine(FormatSpeed(1024000.0, 10.0));

        Console.WriteLine(FormatSpeed(1024000000.0, 10.0));

        Console.WriteLine(FormatSpeed(100 * 1024 * 1024.0, 10.0));

    }

    static string FormatSpeed( double size, double tspan )

    {

      string message = "Download Speed: {0:N0} {1}";

      if( size/tspan > 1024 * 1024 ) // MB

      {

          return string.Format(message, size/(1024*1204)/tspan, "MB/s");

      }else if( size/tspan > 1024 ) // KB

      {

          return string.Format(message, size/(1024)/tspan, "KB/s");

      }

      else

      {

          return string.Format(message, size/tspan, "B/s");

      }

}

}