# Review: Maths Tricks to Blow Your Mind

The chances are, dear Aperiodical reader, that you’re familiar with the following chain of emotions while browsing Facebook:

• Oo! A message from Aunty Jean, I’ve not heard from them in ages!
• Oh. It’s one of those.

I don’t even need to tell you what “one of those” means, do I? It likely has a picture of Einstein. It probably makes a spurious claim about the percentage of people who will fail. I’d make a small bet that it involves the abuse of at least one mathematical symbol.

And, inexplicably, it’ll have thousands of comments stating their answer, generally with a sardonic comment about how those with a differing opinion are fools who should have paid more attention at school.

So, you can imagine the utter delight with which I learned that mathematical comedy singer-songwriter Kyle D Evans had written a book devoted to the viral maths problems that are the bane of any right-thinking person’s existence.

It turns out, a maths teacher with a background in comedy is pretty much the perfect person to write such a book. Evans picks a variety of viral problems, from the obvious dubious obelus we all know and loathe to the far more edifying geometry problems of Catriona Agg, and the borderline useful fact that $$x$$% of $$y$$ is the same as $$y$$% of $$x$$, and he handles them with exactly the attitude they merit: deserved snark, childish curiosity and a sort of “hey! that’s neat! Here’s why it works!” attitude I hope I’d be able to bust out in the pub if someone asked about it.

I’d have liked to see a bit more about the psychology of what makes a mathematical nugget go viral (Evans sort of shrugs his shoulders a bit about this: sometimes things get lots of attention and sometimes they don’t), but this is a very minor quibble about an excellent book. (I’m also disappointed that the phrase “write the bloody thing properly,” the canonical correct answer to annoying Facebook problems, does not appear.)

It’s a book you, a mathematician, can enjoy by reading it; you can also enjoy it by sending it to your Aunty Jean with a note saying “this will explain it.” Aunty Jean is notoriously difficult to buy Christmas presents for. Now you’re sorted.

Maths Tricks To Blow Your Mind, A Journey Through Viral Maths by Kyle D Evans is published by Atlantic Books, £9.99 in hardback, out October 7th 2021.

Colin received a free review copy of the book.