Archive for October, 2012

Charity Shop Maths 2

October 29, 2012

My second charity shop find is the marble puzzle that some of us played with at October MathsJam.

I picked this puzzle up in a charity shop somewhere down south while waiting for my brother to have a job interview this summer. I recognised the puzzle because my other little brother had it as a child and I used to spend hours playing with it after he’d gone to bed, when I was babysitting.

The object of the game is to use the Knight’s move from chess to swap all the blue marbles with the… well… I think they’re brownish, or maybe pink? Anyway, the marbles of the other colour. According to the box, 50-55 moves is average and 45 is excellent. I seem to remember I used to be able to solve it reliably, efficiently and quickly, but having played around with it again I have forgotten all the little tricks and skills I had as a teenager.

If I get any spare time in the next twenty years or so, then implementing a computer version of this puzzle would be an interesting programming challenge. It’s probably already been done, but it’s the sort of thing I can imagine rather enjoying having a go at for myself. Meanwhile, when I get bored of using my Tower of Hanoi as a stress-reliever that lets my mind wander, I have the Knights problem to occupy my hands too.

Charity shop maths 1

October 22, 2012

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.


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?