I was the student who got lost on the first day of geometry class in high school and never got found again. I was glad to find this book, because I thought maybe it would fill in the missing pieces of my geometric education; for example, I thought it would explain to me, in simple terms, why I should care about geometry (admittedly, there is some of that in the last chapter). Renowned mathematician Jordan Ellenberg begins with a section that quotes Wordsworth, and I thought, good! I am in familiar territory! Yet the rest of the book is a highly technical look at earthly phenomena such as pandemics, elections, and artificial intelligence to name a few. I got to the end, but I didn't absorb much.

I'm not sure for whom this book was written, but I am sure it wasn't written for me. ( )

Good meandering explanation of geometry in our everyday lives. (Geometry being a much broader slice of math than I realized. ) I found the first few chapters a little too all-over-the-place but after a while I started enjoying the style and by the end of the book I was really appreciating it. The penultimate chapter about congressional districting and gerrymandering was great - he shows some of the math aspects but also really explores the political and philosophical aspects as well - defining districts is a lot more interesting of a problem then I had realized.

There were a few pages here and there that I just skimmed. It wasn’t that he was doing complex math, he was just going over something relatively simple in a step-by-step way and it felt tedious so I skipped some of those. But that was just maybe a dozen or two pages out of 400.
( )

Just as good as the CBC interview implied. Lots of math, mostly accessible, although truth be told my eyes glazed over at a few points and if I want to grasp and retain the information in the chapters on the pandemic, I will need to re-read. Written with humour. I'll never forget that R-subscript-zero is "Pronounced R-nought, as in 'You R nought worried enough about the next pandemic'". That's a footnote; I missed half the endnotes in the book because I was not expecting a book to have footnotes marked with asterisks as well as Notes unmarked by numbers in the text. ( )

I read Ellenberg's "How Not to be Wrong" about two years ago, and enjoyed his clear explanations of math problems. This was a little less satisfying, athough just as entertaining. In many of his examples I did not see much geometry, and Ellenberg did not always explain the connections. I read one chapter on epidemic propagation twice without getting it down. His nuanced argument about voting districts and gerrymandering was very enlightening. It was also interesting to learn about the connections between statisticians, Poincare and Einstein in the early 1900's.

I marked several passages.
-Poincare was not a visualizer, and would draw a figure from memory by recalling how his eyes had moved along the figure.
-Bachelier, writing in 1900 after analyzing stock and option prices, concluded that mathematically, the expected gain of a speculator is zero
-Mathematicisn Hilda Hudson (working with Ronald Ross, who figured out that malaria was carried by mosquitos and was looking to perfect the mathematics of epidemics) came up with the following epigram in 1910: "The thoughts of pure mathematics are true, not approximate or doubtful; they may not be the most interesting or important of God's thoughts, but they are the only ones we know exactly)
- In English, there are four ways to put the stress on two syllables: unstressed/stresses - an iamb; stressed/unstressed - a trochee; both stressed - a spondee, and neither stressed, a pyrrhus.
- In the discussion of the Fibonacci series, the "golden ratio" appears as a ratio of later terms of the sequence. The golden ratio is exactly given as one plus the square route of 5, dived by 2. The ratio is an irrational number, and it digit order can be shown to be the most random order of all irrationals. ( )

ok, i'll need to read this again and again if i want to follow it all, but I found it fascinating. He writes of how math education could be changed (back?) to a more hands-on, discovery basis and I do think he has a point there. Algebra startled me, geometry befuddled me, calculus -- well. But his examples give you some confidence that with actual thinking time these tools might make sense. ( )