Charity shop maths 1

I have a good excuse for not blogging for a while – over the summer I was finishing my Masters thesis. Now that it is handed in, I’d like to get back into the habit of blogging, so I thought I’d do a short series of posts on my habit of finding mathematical stuff in charity shops. My other half is a record collector so I spend lots of time waiting for him while he browses record racks, and I use that time looking for geeky stuff in among the bric a brac and the books. It was actually from his record collecting that I got the idea of this series of posts; on his record forum they have a ‘charity shop challenge’ where people post about cool stuff they’ve found.

I found this in one of the charity shops in Ely, near Cambridge, some time ago. It looks hand made, and cost a couple of quid.

For those unfamiliar with the old problem, this is a Tower of Hanoi puzzle. The object is to transfer all the rings from one peg to another. You can only pick up one ring at a time, and you can never place a ring on top of a smaller one.

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This shows the puzzle after a few moves have been made. (How many?) Altogether, there are nine rings. I did move all the rings successfully but not all in one go. This was a great find, because I’d been familiar with the Hanoi problem for many years, but actually having a purpose-built puzzle to play with it ‘hands on’ refamiliarised me with the task. If I was introducing the problem to kids, I’d want them to have something to manipulate. When we were little, we used to do it with the brass weights that went with the kitchen scales, as they were little discs of different sizes that stacked.

Have you met the Tower of Hanoi before? Have you used it in a classroom or masterclass situation? Have you ever found anything cool, mathematical and geeky in a charity shop?