int won = 123456890; Console.WriteLine(string.Format("{0:n0}", won)); Console.WriteLine(string.Format("{0}", won.ToString("n0"))); ; Console.WriteLine(string.Format("{0:#,##0}", won)); Console.WriteLine(string.Format("{0}", won.ToString("#,##0"))); //결과 //123,456,890 //123,456,890 //123,456,890 //123,456,890