using System;

​

public class Program

{

    public static void Main()

    {

        var newN = new TN();

        newN.testme = 12345.23m;

        newN.testnullable = 232.343m;

        newN.testnullnullable = null;

        Console.WriteLine($"Hello World {newN.testme:C2} nullable: {newN.testnullable:C2} Nullthing: {newN.testnullnullable:C2} Nullthing: {newN.testnullnullable:C}  NullthingN: {newN.testnullnullableN:C2}");

        Console.WriteLine($"{newN.testnullnullableN == null} Hello World C only {newN.testme:C} nullable: {newN.testnullable:C} Nullthing: {newN.testnullnullable:C}  NullthingN: {newN.testnullnullableN:C}");

    }

​

    public class TN

    {

        public decimal testme { get; set; } = 12345.23m;

        public decimal? testnullable { get; set; } = 232.343m;

        public decimal? testnullnullable { get; set; } = null;

        public decimal? testnullnullableN { get; set; } = null;

        public string TotalPaidFormatted

        {

            get

            {

                return $"{this.testnullable:c}";

            }

        }

    }

}