Quickest way, and without any tools:
You could type 24 into a document, then use Alt+X to toggle the code into
the corresponding character ($).
That works in the other direction, too, and even in dialogs like
Find/Replace.
There are code page tables for the old Windows code page 1252 like the one
from Wikipedia:
http://www.microsoft.com/globaldev/reference/sbcs/1252.mspx
Some show both the hexadecimal and decimal code:
http://www.kostis.net/charsets/cp1252.htm
You could also calculate the decimal code from the hex code (hex 24 = 2×16+4
= 36, so you could type Alt+36 to get $), or use the Windows calculator from
the accessories in scientific view.
Klaus