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## Category Archives: Edited by Samuel Hansen

### How to calculate π

How would you calculate ? I remember being sent as a boy of ten into the schoolyard to find circular objects to measure. Our attempts to wrap a tape around a dustbin lid clearly did not represent the optimal method. Perhaps you know a few digits of . Starting from scratch, how would you find […]

### Why the hot light bulb annoys me

The light bulb puzzle presents you with three switches, one of which controls a light bulb inside a closed room. You are permitted to flip switches as much as you like, then you must open the door and say which switch controls the light bulb. You don’t seem to have enough information. You can flip […]

### Fundamental principle behind many dynamical systems verified

Diffusion is a physical process that is an essential component of innumerable phenomena in nature, including when your lungs transfer oxygen into and carbon dioxide out of your blood. Now a fundamental principle behind diffusion has at last been experimentally verified. An ergodic dynamical system is one for which the average behaviour of a single […]

### Hardy’s Apology: what’s to dislike?

In recent years I’ve felt quite glad I never read G.H. Hardy’s massively influential book A Mathematician’s Apology (1940). I’d heard of this by the time I arrived at university but never got around to borrowing the copy I saw in the Hall library. Recently I decided to take a look and found much to […]

### Moving on a strange diagonal

Here is a puzzle I enjoy giving to students. Given a 4×4 grid of sixteen dots, draw six straight lines that form a continuous path passing through all of the dots. Here, continuous means you must be able to draw over your six lines in one go without taking your pen off the paper. This […]