NumberFormatInfo.Currency Group Sizes
using System; using System.Globalization; class NumberFormatInfoSample { public static void Main() { NumberFormatInfo nfi = new CultureInfo( "en-US", false ).NumberFormat; Int64 myInt = 123456789012345; Console.WriteLine( myInt.ToString( "C", nfi ) ); int[] mySizes1 = {2,3,4}; int[] mySizes2 = {2,3,0}; nfi.CurrencyGroupSizes = mySizes1; Console.WriteLine( myInt.ToString( "C", nfi ) ); nfi.CurrencyGroupSizes = mySizes2; Console.WriteLine( myInt.ToString( "C", nfi ) ); } } //$123,456,789,012,345.00 //$12,3456,7890,123,45.00 //$1234567890,123,45.00