I’ve been having fun reading books on math lately. The first was Zero: The Biography of a Dangerous Idea by Charles Seife. The second was Humble Pi: A Comedy of Math Errors by Matt Parker. Both made me wonder why I wasn’t a math teacher. So then I took an online algebra class during the pandemic and got my answer. Still, I liked reading about math, so when I saw Pluses and Minuses available as an ARC on NetGalley, I was pretty excited.
In the introduction it became clear what kind of math I was going to be reading about -- not the calculation drudgery (which I both love and loathe) but the kind that solves problems. And the first problem it mentions was this: “We can only learn how to combat fake news if we understand how internet services strengthen our opinions and why it’s not easy to change the way they do that.” This is the kind of thing I’m trying to communicate to my students when I’m telling them that math really, truly, sincerely IS important in every aspect of their daily lives, but it’s what I have the hardest time communicating because my pedagogical realm is so divorced from math. Then I was promised that the “ideas behind [statistics and calculus] are often unexpectedly simple and much more useful than you might suspect from what you learned at school”. I’m decently comfortable with statistics, but I’ve always wanted to actually understand what the heck calculus is for.
I didn’t expect to start with the how babies think about quantity and shape, but that’s where the book went pretty early on, and it was fascinating (and might even explain why I find geometry easier than algebra). That moved on to the history of the development of math (including some word problems from 1740 B.C. -- not much has changed!) A little historical tidbit I enjoyed: “The head of a temple [in ancient Egypt] was paid exactly thirty times more than the lowest laborer.” If only we had a cap like that on CEO salaries…
My main beef with the book is that sometimes it makes references to mathematical principles without any explanation of what that principle is. Here are a couple examples: 1.“Archimedes...discovered his famed principle of fluid dynamics.” I know I learned what that is, but off-hand, I can’t remember.
2. “Ratios are in fact fractions… but, instead of ⅔, they wrote them in a more complicated way.” I want to see that way!
A little parenthetical or footnote would erase the need to have Google at the ready while reading. It is entirely possible that footnotes and end notes were not available in the advanced reading copy (that happens), and if that is the case, then you won’t have to worry.
The discussion of pi was great. The author argues that “no one finds it strange if we talk about pi. We’ve become so used to numbers like this that they only seem peculiar when we think about them a little longer.” To that, I say, speak for yourself. Pi and other numbers that can’t be expressed completely have always given me a headache. It doesn’t matter if I’m just plugging it into a simple expression like A=πr2, I still end up spending at least ten minutes wondering things like, “If this calculator only uses a portion of pi in the calculation, then can we ever get a truly accurate answer to what the area of this circle is?” These meanderings are probably why I rarely ended up finishing my math homework. He writes about how 0.999… is actually equal to 1, and my brain explodes. At least he acknowledges that “[i]nfinity soon makes your head spin.” I have a lot of respect for people who can spend their days calculating to create actual, physical results (like getting a plane to fly or, his example in this chapter, making cruise control on a car work) while grappling with numbers and ideas that cannot be expressed. Sure, you can make a little symbol for it, but can you really imagine infinity?
This topic led to what I was most excited about going into this book: an explanation of calculus. I can’t now do calculus, and if you asked me to explain how and why it came to be, I would likely just quote from this book, but I feel satisfied that I have a much better understanding of what it is and how it works. I’m still stuck with the Greeks, though, in having “a problem with infinity” and thinking no one can calculate with that. Understanding calculus, to me, requires a leap of faith that my brain seriously struggles with. When I read the explanations for calculus, I get it momentarily, and then it fades away, and I have to remind myself why it works. I’m hoping to brush up my math sills and take an introductory calculus class soon (once schools meet in person again; I’m not sure I could handle it in a distance-learning situation). I even already purchased the calculator for it. Maybe with daily exposure, I’ll finally be able to hold on to my understanding for more than a fleeting moment. (A plus from this book that will serve me well: I learned what differentials and integrals are.) The author makes a good argument for understanding the ideas behind calculus even if we choose careers (as I have) that do not require that we use it. It’s not far from the reason I tell my students why they need to understand at least the very basics of science even if they won’t be pursuing science in the future -- it’s a matter of understanding how our world works, and if we don’t have a basic understanding, then we are much more likely to be fooled by lies and poor (or intentionally misleading) reasoning which affect who we vote for and what those people who decide the quality of our daily lives choose to do. They can easily choose to benefit themselves over us if we are not both skilled and informed.
We move on from calculus to statistics, a subject I am infinitely (I have infinity on the mind) more comfortable with. I’m no expert, but I enjoy the topic, especially the analysis of what people think data implies versus what data actually implies. It has taught me to be critical of any implications and assumptions I see extrapolated from statistics shared in the news, and that has proven very useful. I did appreciate that this section, but for two, used examples not beaten to death in other books on statistics.
Then we go on to graph theory, which, to be honest, is something I didn’t know was a theory. I thought graphs were just visual representations of data. Who knew? Not I, obviously. It turns out this is the theory behind what Google searches recommend, how to predict the effectiveness of certain cancer treatments, and how computers “learn”. (I had a bit of a War Games flashback during that last section.) This all, unfortunately, leads to abuses of the information gathered with this tool, and they are way scarier than what is possible with statistics (and the manipulation of statistics are scary enough!). I didn’t know I didn’t know about graph theory, and it ended up being my favorite part of the book.
I’d definitely recommend this one. It’s not exhaustive on any of the subjects, but it provides an explanation, examples, and the importance of different fields of math with some interesting history and an overview of the problems in each. I think it’s a good starting point for anyone interested in learning more, and I wish this were how math was introduced to me in school. If I knew why certain skills were useful, I would have spent a lot more effort trying to master them.