You know what the biggest problem with *The Maths Behind* is? ‘Ice Col’ Colin Beveridge has basically covered every possible topic we can ever blog about on the Chalkdust website. This book explores the maths behind **57** everyday events: that’s more than a year of blog posts!

If this doesn’t strike you as a particularly large problem, then I reckon you will enjoy this book.

The first thing that strikes me about this encyclopedia of mathematical modelling is that it is very pretty. The publishers produce a lot of cookery books, and their designers have done a really rather good job of bringing these fifty-or-so topics to life. Most topics cover two to four pages, with large colourful graphics.

The witty text wraps around these graphics nicely, and it’s one of the standout features of this collection. Fans of silly jokes will particularly enjoy the index:

A to B, getting from… page 7

A to X, getting from… page 151.

Colin has good stock in taking mathematics and making it accessible and entertaining. Last year he published *Cracking Mathematics*, and before that his *Maths for Dummies* series has done rather well. The podcast he has co-hosted with Dave Gale since 2013, *Wrong, But Useful*, perhaps has provided fertile ground to collect interesting maths applications, and to find the fun in them. I’ll let you discover what he cheekily asks Siri on page 82.

## A nice selection of topics

The book (dare I say, magnum opus) is arranged into seven themes—the human world, technology, entertainment; that sort of thing—and you are actively encouraged to dip into a topic.

I don’t know who came up with the list of topics, but it’s nice to see a book like this tackle some important and current problems, as well as some classics. Some nice graphics show the dangers of gerrymandering, and a cute use of the binomial distribution tells you it’s basically never worth voting. Ah well. Top tip, though: if you drop your toast, flip it as much as possible to offset its natural tendency to fall butter-side down.

Many of the topics have an important equation circled at the top of the page. And these are often not easy equations! I was particularly pleased to see the Péclet number—an important ratio in fluid mechanics—appear in a discussion of penguins huddling. The Black–Scholes equation—a partial differential equation modelling the price evolution of financial derivatives—also makes an appearance (although, aha, I spot a typo!). It’s quite hard to put a second order nonlinear PDE in a book like this, but Colin does a good job of explaining their meaning. The explanation of logarithms in the discussion about the technically-not-really-Richter scale I found satisfyingly succinct and clear.

Despite already covering 57 topics, the book is littered with extra fun facts. There are nice short biographies of some of the key players in the models. And in a section on ‘pilish’—writing such as “how I wish I could recollect of circle round”, where the length of each word gives rise to an important sequence—Colin can’t help but reference the conjectured normality of pi.

## A book for… maths talks

As someone who gives pop maths talks relatively frequently, it is extremely tempting to take this book and think “here are dozens of things I could write talks about”. Is that allowed? Would you sue me, Colin?

Perhaps some of the research for book actually started with Colin’s wide knowledge of what’s happening on the pop maths scene. The section on romance reminds me of Hannah Fry’s book; the sports chapter treads some of the same ground as Rob Eastaway. Maybe I’ve forgotten how print media works but I found myself wishing I could find out more quite often, and there aren’t any obvious references.

If I may add some niggles. For some odd reason(!), the publishers have opted not to use LaTeX, and the equations are a bit of a typesetting mess. It’s a shame because the graphics are otherwise lovely. (I imagine this irks Colin just as much.)

Despite the British spelling, there are -izes, Titles Capped Up Like This, and inconsistent mixes of metric and imperial units. It’s just a bit awkward to have sentences like

“An American pool ball is 5.7cm (2¼ inches) in diameter, while the mouths of the corner pockets are…between 11.4–11.8cm (4¼ and 4⅝ inches); the side pockets are…1.3cm (half inch) wider.”

Yes, yes, the pedant in me appreciates the correct use of fractional inches rather than decimal inches, but this is one of those traits of cookery books that didn’t really need to be carried over. Is anyone really using $g=32\mathrm{ft}/\mathrm{s}^2$ any more?! I suspect, given the pages on baseball and American football, that this is going pretty much unedited into the American market.

Those of us in the maths outreach community often tell people that ‘maths is in everything’. But if we’re not careful, in trying to explain how, we sweep the maths under the carpet. At the beginning of this book, Colin says that you don’t need any mathematical knowledge to read this book. For most of the book, this is probably true, and in fact the book manages to walk the line between being readable and demonstrating how it works very well. It’s not shy in showing you the actual mathematics, and it demonstrates how to present this in an accessible way.

It’s a smart way to appeal to both maths fans and the sci-curious. Pop it in a stocking, or pop it in your toilet this Christmas.

*The Maths Behind* by Colin Beveridge is published by Octopus Books and retails at £14.99.