wrt the previously posted request i too am in need to implement something like David was asking.
it's once again down to realising a match captcha, similar to what BestWebSoft have achieved with their Captcha plugin, capable of receiving answers both in numeric and letters forms.
i.e. to the captcha question "three+2=" one can either answer "5" or "five".
of course i can add a "numbers only, please" label, but was wondering still if something like the above is doable.