Anyone work anything about innumeracy into their math magic routines? I remember a teacher who did this...honest man

Interesting… just wondering in what way you are thinking about it being part of a routine? Maybe to point out the fact and/or make light of a person's lack of mathematical skill (in a fun way, not in a condescending or insulting way I assume?). Or maybe to capitalize on innumeracy as a “gimmick” (so to speak) to accomplish your effect (i.e. the mathematical deficiency of your audience allows you to perform mathematical based effects without fear of your method being detected or deduced)?