.NET Fiddle

CSharp · Console

/Program.cs

using System;
					
public class Program
{
	public static void Main()
	{
		double number1 = 10000000,
			   number2 = 10000000.234,
			   number3 = 10000000.05;
		Console.WriteLine(number1.ToString("##,#0.##"));
		Console.WriteLine(number2.ToString("##,#0.##"));
		Console.WriteLine(number3.ToString("##,#0.##"));
	}
}