using System;
using System.Drawing;
using System.Text.Json;
using Newtonsoft.Json;
using System.Globalization;
public class Program
{
public static void Main()
var amount = 12345.0000M;
var cultureInfo = CultureInfo.GetCultureInfo("en-US");
var formattedAmount = String.Format(cultureInfo, "{0:N2}", amount);
Console.WriteLine(formattedAmount);
Console.ReadLine();
}