Back to basics

At the charity shop this afternoon, and the ancient till finally gave up the ghost! We were back to pen, paper and a good old fashioned calculator. Then it got competetive; my co worker, in her eighties, decided that we should exercise our brains and throw out the calculator, to see who was best a mental maths! I didn't win, she was far too quick for me! Only hope that my brain is as good as hers when/if i get to that age!