C# Numbers - Formatting

msdn - dwhawy9k

Dim sResult As String 
sResult = System.String.Format("Total is {0}", 123.45) 
sResult = "The total is 123.45"

When the argument is numeric you can add a colon after the argument index followed by a character to specify the numerical format.

sResult = System.String.Format("Total is {0:C}", 123.45) 
sResult = "The total is $123.45"

You can also append an integer after the argument index to indicate the number of decimal places.

sResult = System.String.Format("Total is {0:C1}", 123.45) 
sResult = "The total is $123.5"

G or g	General - Displays the number in either fixed-point or exponential format depending on which format delivers the most compact result.
N or n	Number - This includes the thousand separator.
C or c	Currency
D or d	Decimal - Only works with Integer values.
E or e	Scientific - Displays the number as n.nnnnE+eeee
F or f	Fixed-point
P or p	Percent - Displays the number as a percentage with decimal places as default.
R or r	Round-trip
X or x	Hexadecimal

You can also build you own custom number format by using any of the following special characters.