I spent most of last week telling everyone I could think of about Amy’s insight into the Envelope puzzle, and I couldn’t wait to throw some of my more difficult puzzles at her and her partner. I gave them a ten-envelope set where each contains two cards from a 1 to 20 set, and the displayed products are 10, 24, 26, 45, 55, 63, 136, 168, 320, 342.
They dealt with this quite happily, so I gave them a smaller set, with just four envelopes and a set of 1 to 12 cards – but three cards to an envelope and their products shown:
Once again Amy did something I didn’t expect. Padraig, much as I would have done, targeted the 14 envelope and deduced it contained the 1, 2, and 7. But Amy zoomed straight in on the biggest number, treated it as 96 x 10, recalled that 96 is 12×8, and was home and dry.
What I can’t get my head around is that she’s got brilliant things about how numbers work going on in her head and yet she’s someone who hasn’t found much success in maths. I’m going to have to devise something really special for next week.