When I go shopping, one action that never fails to amuse me is the way counter sales persons and cashiers use calculators to do their sums, even for the smallest of calculations.
Even standing across counters and with the documents being written or read upside down to me, I usually finish the calculations before they do, using just mental arithmetic skills. Skills that I was forced to learn in school and by a tiger father at home. The basic skill of course was learning multiplication tables right side up and upside down and with random questions being thrown at unexpected times, for which if answers were not immediately forthcoming, punishment was immediate and harsh.
One of the punishments that I used to suffer has now become a Yoga technique, and Padmum in her post Exercise For Memory. Please read my comment on that post to understand what I mean in this post.
I now wonder whether it was really punishment or just an excuse to improve our memory skills!