there's some info about that on wookieepedia: http://starwars.wikia.com/wiki/Aurebesh
in some writing systems (http://en.wikipedia.org/wiki/Greek_numerals), numerals simply use the alphabet symbols -- the first letter for 1, the second letter for 2, etc. i would suggest that if somebody were to take this up, they could follow a similar system w/ aurebesh.