Any book on cryptography written for a more-or-less lay audience must inevitably face comparisons to *The Code Book*, written in 1999 by Simon Singh, the king of distilling complex subjects to a few hundred pages of understandable writing. While Singh’s book is a pretty thorough history of codes and codebreaking through the centuries with plenty of the maths thrown in, *The Mathematics of Secrets* is tilted (and indeed titled) more towards a fuller explanation of the mathematical techniques underlying the various ciphers. Although Holden’s book follows a basically chronological path, you won’t find too much interest in pre-computer ciphers here: Enigma is cracked on page seventy, and the name Alan Turing does not appear in the book.

# Video: How to draw an egg

Katie’s done another video! This time it’s a neat method for constructing an egg-shape, using arcs of circles.

Bonus challenge: See if you can count how many times Katie accidentally says ‘compass’ instead of ‘pair of compasses’ during the video.

# Timetabling choreography with maths

Earlier this week my sister-in-law (“SIL” from now on) sent me an email asking for help. She’s a dance teacher, and her class need to rehearse their group pieces before their exam. She’d been trying to work out how to timetable the groups’ rehearsals, and couldn’t make it all fit together. So of course, she asked her friendly neighbourhood mathmo for help.

I’d half-remembered Katie’s friend’s Dad’s golf tournament problem and made a guess about the root of the difficulty she was having, but on closer inspection it wasn’t quite the same. I’m going to try to recount the process of coming up with an answer as it happened, with wrong turns and half-baked ideas included.

# Carnival of Mathematics 144

The next issue of the Carnival of Mathematics, rounding up blog posts from the month of March, and compiled by Frederick, is now online at White Group Mathematics.

The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.

# Video: New mathematical card trick

I’ve done another maths video! If you missed it earlier this week, here’s a nice mathematical card trick I learned recently on a trip to Finland. Enjoy!

# A day in the life of a maths e-learning officer

My wife’s school recently sent round a form with questions about “a day in the life” of people working in STEM careers, to show to their year 6 children. My job involves the M in STEM, so I agreed to have a go at describing my day.

I quite enjoyed describing about what I do, so I’ve decided to reproduce my answers here. Enjoy!

# Cutting an oval pizza – video

As if there wasn’t enough maths/pizza news lately, the story has hit the red-tops recently that UK supermarkets are scamming consumers by offering them oval-shaped pizzas – marketed in the high-end/’Extra Special’ ranges, with more expensive (sounding) ingredients like *mozzarella di bufala*, *roquito peppers* and *merguez sausage*, and a distinctive pair of artisanally different radii. These pizzas apparently cost more per gram, because their elliptical shape means they’re actually smaller than a circle with the same diameter. Cue plenty of ‘costing you dough’ and ‘cheesed off’ puns.

While we’re not massively bothered by the pricing, the articles do raise, and then completely fail to address, an interesting point: an oval pizza is harder to cut into equally sized pieces! Luckily, maths is here to save the day. I found a nice method and made a video explaining how it works:

Take a look and improve your future pizza cutting technique!