using System;

using System.Globalization;

​

public class Program

{

        public static void Main(string[] args) {

            NumberFormatInfo nfi = new CultureInfo( "en-US", false ).NumberFormat;

​

            // Displays the same value with a blank as the separator.

            Int64 myInt = 1234567890;

            nfi.NumberGroupSeparator = ".";

            Console.WriteLine( myInt.ToString( "N0", nfi ) );

        }

}