C# Numeric (“N”) Format Specifier

The numeric ("N") format specifier converts a number to a string of the following form −

"-d,ddd,ddd.ddd…"

Above,

• "-" is a negative number symbol if required,
• "d" is a digit (0-9), "," indicates a group separator,
• "." is a decimal point symbol

Example

 Live Demo

using System;
using System.Globalization;
class Demo {
   static void Main() {
      double val1 = -5566.789;
      Console.WriteLine(val1.ToString("N", CultureInfo.InvariantCulture));
      int val2 = 87987766;
      Console.WriteLine(val2.ToString("N3", CultureInfo.InvariantCulture));
   }
}

Output

-5,566.79
87,987,766.000