If you want a challenge, try this one: http://twiki.org/p/pub/Codev/TWikiPresentation2013x03x07/reg...
https://devjoe.appspot.com/huntindex/puzzle/mit2013601
PDF: http://web.mit.edu/puzzle/www/2013/coinheist.com/rubik/a_reg...
The puzzles generally don't tell you how to extract the answer, but the idea is you know it when you see it.