Wouldn't it be useful to have numbers above ten used? I'm kind of hazy on how one constructs "twenty-three" or "two thousand one hundred and six" or the like.
After 'zehn' comes 11 'elf' and 12 'zwölf', then 13 'dreizehn', 14 "vierzehn', etc. up to 20 'zwanzig', then it's 21 'einundzwanzig', 22 'zweiundzwanzig', etc., to 30 'dreizig', and similarly to 100 'hundert'. 2106 is 'zweitausendeinhundertsechs'.
I think this link sums it up pretty well: http://www.bbc.co.uk/languages/german/lj/language_notes/11_99.shtml
My first language is English but my parents are both German. This always gets me too. :) The only thing that I have to add is that ALWAYS make sure to put ones place before the tens place. 'Einundzwanzig' (ein und zwanzig) NOT the other way around.