double value;

 value = 123;
 Console.WriteLine(value.ToString("00000"));
 Console.WriteLine(String.Format("{0:00000}", value));
 // Displays 00123

 value = 1.2;
 Console.WriteLine(value.ToString("0.00", CultureInfo.InvariantCulture));
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                   "{0:0.00}", value));
 // Displays 1.20

 Console.WriteLine(value.ToString("00.00", CultureInfo.InvariantCulture));
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                 "{0:00.00}", value));
 // Displays 01.20

 CultureInfo daDK = CultureInfo.CreateSpecificCulture("da-DK");
 Console.WriteLine(value.ToString("00.00", daDK));
 Console.WriteLine(String.Format(daDK, "{0:00.00}", value));
 // Displays 01,20

 value = .56;
 Console.WriteLine(value.ToString("0.0", CultureInfo.InvariantCulture));
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                 "{0:0.0}", value));
 // Displays 0.6

 value = 1234567890;
 Console.WriteLine(value.ToString("0,0", CultureInfo.InvariantCulture));	
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                 "{0:0,0}", value));	
 // Displays 1,234,567,890

 CultureInfo elGR = CultureInfo.CreateSpecificCulture("el-GR");
 Console.WriteLine(value.ToString("0,0", elGR));	
Console.WriteLine(String.Format(elGR, "{0:0,0}", value));	
 // Displays 1.234.567.890

 value = 1234567890.123456;
 Console.WriteLine(value.ToString("0,0.0", CultureInfo.InvariantCulture));	
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                 "{0:0,0.0}", value));	
 // Displays 1,234,567,890.1

 value = 1234.567890;
 Console.WriteLine(value.ToString("0,0.00", CultureInfo.InvariantCulture));	
 Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                 "{0:0,0.00}", value));	
 // Displays 1,234.57

double value;

value = 1.2;
Console.WriteLine(value.ToString("#.##", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:#.##}", value));
// Displays 1.2

value = 123;
Console.WriteLine(value.ToString("#####"));
Console.WriteLine(String.Format("{0:#####}", value));
// Displays 123

value = 123456;
Console.WriteLine(value.ToString("[##-##-##]"));
Console.WriteLine(String.Format("{0:[##-##-##]}", value));
 // Displays [12-34-56]

value = 1234567890;
Console.WriteLine(value.ToString("#"));
Console.WriteLine(String.Format("{0:#}", value));
// Displays 1234567890

Console.WriteLine(value.ToString("(###) ###-####"));
Console.WriteLine(String.Format("{0:(###) ###-####}", value));
// Displays (123) 456-7890

double value;

value = 1.2;
Console.WriteLine(value.ToString("0.00", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:0.00}", value));
// Displays 1.20

Console.WriteLine(value.ToString("00.00", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:00.00}", value));
// Displays 01.20

Console.WriteLine(value.ToString("00.00",
                  CultureInfo.CreateSpecificCulture("da-DK")));
Console.WriteLine(String.Format(CultureInfo.CreateSpecificCulture("da-DK"),
                  "{0:00.00}", value));
// Displays 01,20

value = .086;
Console.WriteLine(value.ToString("#0.##%", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:#0.##%}", value));
// Displays 8.6%

value = 86000;
Console.WriteLine(value.ToString("0.###E+0", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                  "{0:0.###E+0}", value));
 // Displays 8.6E+4

double value = 1234567890;
Console.WriteLine(value.ToString("#,,", CultureInfo.InvariantCulture));	
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:#,,}", value));	
// Displays 1235

Console.WriteLine(value.ToString("#,,,", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:#,,,}", value));
// Displays 1

Console.WriteLine(value.ToString("#,##0,,", CultureInfo.InvariantCulture));
Console.WriteLine(String.Format(CultureInfo.InvariantCulture,
                                "{0:#,##0,,}", value));
// Displays 1,235