It has come to my attention that my book *Math with Bad Drawings *has some errors.

(And no, it’s not that a few good drawings slipped through.)

This fallibility should surprise no one. My editorial team is full of heroes, but with an author like me, mistakes are inevitable. Especially on difficult tasks like, say, shopping for produce, or not walking face-first into parking meters.

I would love to correct these errors, but the book is a victim of its own success: as the hardcover continues to sell like misshapen hotcakes, it may be a while before we do a paperback or a second edition.

In the meantime, I will document the errors below, updating the list whenever a new one comes to my attention. Please feel encouraged to comment with any additional typos that you’ve noticed!

**Page 36: “Borromean” rings**

Here is a beautiful idea: three rings intertwined, such that if you remove any one of them, the other two separate. They are linked not as pairs, but only as a trio.

With this lovely trait, the Borromean rings can serve as a lovely metaphor for many things. A delicate political alliance. Sternberg’s triarchic theory of love. Perhaps even the Christian trinity. (Having read some G.K. Chesterton and C.S. Lewis, it is my understanding that basically everything is a metaphor for the Christian trinity.)

Unfortunately, I did not draw Borromean rings.

I drew two linked rings, with an extraneous third ring snuggled up alongside them, desperately pretending that it matters. This is a much less useful metaphor, although it does resemble my behavior while my wife is bonding with a stranger’s dog.

I thank Damaris O’Trand and others for bringing this error to my attention.

**Page 56: m vs. cm**

In this passage, I urge you to build a triangle of side lengths 5, 6, and 7 meters. This unwieldy monstrosity will no doubt occupy your entire yard, prompting squabbles with the neighbors. Your only solace is that I have promised to build one too.

But then, I betray you! The drawing shows that I have constructed instead a petite, portable triangle with sides of 5, 6, and 7 *centimeters*.

I apologize for this devious switch (and I apologize also to the kind soul who pointed it out to me and whose name I have misplaced).

**Chapter 7: Irrational Paper**

In my zealous advocacy for A4 paper, I went too far. Perhaps this is why they call me “Overzealous Orlin.”

(NOTE: please, no one call me Overzealous Orlin.)

It is slander to say that 8.5″ by 11″ paper bears no relation to larger or smaller sizes. Two sheets yield the next size up (11″ by 17″), and half a sheet yields the next size down (5.5″ by 8.5″). In that sense, it’s just good as A4.

But there’s a problem. While 8.5″ by 11″ has a long-side-to-short-side ratio of 1.29, its neighbors each have ratios of 1.55. They are, in short, different shapes. If you’ve ever tried enlarging or scaling down a photocopy, you recognize the madness this causes.

What makes the A-series special is its *proportionality*. Every paper in that glorious sequence is a similar rectangle, a scaled version of its brethren.

I knew all this when I was writing the chapter, yet I allowed the heat of rhetoric to carry me too far. I thank Joe Sweeney for the correction, and I apologize to 8.5″ by 11″ paper: you are still inferior, of course, but not as inferior as I suggested.

**Page 225: “Singles”**

In writing *Math with Bad Drawings*, I did my best to shun the kind of daunting technicality that drives so many from the gates of mathematics. So please forgive me for diving into the weeds here, but grasping this miscue requires real sophistication; a doctorate will help.

The text above asserts that a “single” in baseball is worth 2 bases.

It also asserts that 12 x 2 = 12.

Now, these claims may look perfectly credible to the outsider. But expert sabermetricians will recognize a small yet meaningful error in the first claim. Meanwhile, number theorists may be able to spot a minor inaccuracy in the second.

I thank Andrew Fast for calling this to my attention.

**Page 337: “Stage” Dead**

I meant to write “stay dead.”

Though actually, “stage dead” could be a cool new idiom.

So you know what? I do NOT regret this error. Come at me, grammarians!

I wanna read your book so I could figure out why there is text which says Stay dead

Guessing from the few details I see, that looks a lot like he was describing John Horton Conway’s “game of life”, a cellular automaton composed of a square lattice of cells, each of which can be “live” or “dead” at each tick of time. Each cell has eight neighbours (four diagonally, four sharing an edge with it). Count how many live neighbours each cell has, at a given tick of time: if it has more than three or less than two, it’ll be dead at the next tick; if it has three live neighbours now, it’ll be live next tick (regardless of what it is now); if it has two live neighbours now, it’ll be the same next tick as it is now (so it’ll stay live if live but stay dead if dead). The pictured square of four live cells, surrounded by dead ones, is stable; each live cell has three live neighbours, so is live next tick; dead cells at a corner have one live neighbour, so are dead next tick; dead cells along a side have two live neighbours, so stay as they are, dead. For a web implementation, I can offer you: http://www.chaos.org.uk/~eddy/craft/weblife.html

Thanks!!!

Thank you for these corrections, Overzealous Orlin. May your zeal be bounded in the years to come.

I don’t have a correction, but a comment. I bought your book because I thought I would enjoy it. I did. But what I was to share is that my 11 year old has declared a renewed passion for math as her favorite subject because of it. She has been quoting it and looking eagerly for mathematical subject material beyond the algebra she is getting in school. Go Bad Drawings!

Thanks, Megan – I’m honored that you both enjoyed it, and especially happy that she’s inspired to dig deeper into math!

In the first note on part II, it says that for a pentagon with equal corners, every corner is 180 degrees. Last time I checked, it was 108 degrees. So the ‘0’ and ‘8’ are mixed up. Don’t know if this is in the original version, or if it’s a mistake by the Dutch translator.

Thank you – noted! And I hope you’re enjoying the Dutch version!

Note to self, via Ray Cavender: 12 times 9 is not 96.

cf: Chapter IV, Section 7 The Variance (And The Standard Deviation), 8th para: “In particular, a single outlier…(e.g., 3**2 = 9; 12 such terms total to just 96)”