http://stackoverflow.com/questions/228532/difference-between-char-isdigit-and-char-isnumber-in-c-sharp

Char.IsDigit() is a subset of Char.IsNumber().

Some of the characters that are ‘numeric‘ but not digits include 0x00b2 and 0x00b3 which are superscripted 2 and 3 (‘²‘ and ‘³‘) and the glyphs that are fractions such as ‘¼‘, ‘½‘, and ‘¾‘.

Note that there are quite a few characters that IsDigit() returns true for that are not in the ASCII range of 0x30 to 0x39, such as these Thai digit characters: ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘ ‘?‘.

This snippet of code tells you which code points differ:

static private void test(){    for (int i = 0; i <= 0xffff; ++i)    {        char c = (char) i;        if (Char.IsDigit( c) != Char.IsNumber( c)) {            Console.WriteLine( "Char value {0:x} IsDigit() = {1}, IsNumber() = {2}", i, Char.IsDigit( c), Char.IsNumber( c));        }    }}

Difference between Char.IsDigit() and Char.IsNumber() in C#