I’m finished with the arguments between p and 2 pi. Henceforth, I shall follow 8 pi and be one of the octopi — the mathematicians of the sea! You can buy this T-shirt at SnorgTees along with many other great T-shirts with a science...

When all the Pi is Wrong nonsense stormed the internet I had many responses to my video and it wasn’t all just hate mail and “how did this guy get a PhD when he finds dividing by 2 difficult?”. One assertion in particular gathered a lot of interest. I got comments ranging from bewilderment to abuse. My inflammatory statement: a 50 pence coin has constant width. It’s an amazing counterintutive idea that there exist shapes that have constant width but are not circular. The 50 pence coin – which to non-Britons probably looks more like a martial arts weapon than national currency – has such a shape. It’s a wonderful design and now it and the 20 pence coin are considered design classics. Nonetheless, Alex Bellos notes in his recent Royal Society Winton Prize nominated book that initially there was a campaign against it because the Queen would be “insulted by this heptagonal monstrosity”. (If you haven’t read Bellos’s book, then go buy one now!) There is more to it than just looks. It is practical. The shape allows visually impaired people to tell what the coin is without having to carefully judge the size. (Judging coin size can be difficult – many old people suffer from both sight problems and arthritis.) Of course, if you wanted a coin that is an easily detectable shape, then why not use a square? Well, then the problem is how do you get a vending machine to detect coin values? You will need an extra mechanism to detect shapes and one to orient the coin to check its size in case it is a fake. The underlying mathematical beauty of the 50 pence is that wherever you measure its width it is the same and hence the...

Two recent and complementary articles about maths and music: Listen by numbers: music and maths by Marcus du Sautoy. The enduring myth of music and maths by Tim...

What a crazy week that was! My heartfelt thanks to everyone who has sent comments, suggestions and criticisms via email and YouTube. I was truly surprised by the response. I’ll blog soon about some issues that arose, in particular the Rhind Papyrus and 50 pence pieces! In the meantime some facts and links: The tau versus pi story was more popular than I expected and I appeared on radio and TV (as you can see above). The Times online article was Top 5 most read during Tau Day and the BBC online article was Most Popular two days in a row in the science and technology section. The video has had over 60,000 views on YouTube, was #51 most viewed video in Science and Technology for UK and #83 for the week in Science and Tech (globally). Various articles appeared in English, certainly far too many for me to list. Here’s a selection of foreign language articles: Portuguese Chinese Russian Spanish...