Humble Pi: When Math Goes Wrong in the Real World – Matt Parker

Thoughts: A fun, light read. Not much by the way of new concepts, but good for a few chuckles.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering. I read this as an e-book, so page numbers are as they appeared in the app I used, Libby. Which is unfortunate, because a physical copy would have had reversed page numbers.)

Parker, Matt. 2020 [2019]. Humble Pi: When Math Goes Wrong in the Real World. Riverhead Books.

Zero: Introduction

One: Losing Track of Time

Two: Engineering Mistakes

Three: Little Data

• 74: Reminder: Excel is no substitute for a database, particularly because excel can easily confuse data types. Telephone numbers, for example, are strings and not numbers, but spreadsheet software doesn’t know that.
  • subsequent pages: Excel also does a terrible job dealing with hexidecimal (it can convert into base-16 in one step of a calculation, and forget that it’s dealing with a base-16 number in the next step)

Four: Out of Shape

Five: You Can’t Count on It

• 122: He did it! He called out the terrible 1-indexing convention when counting musical intervals! Everywhere else, 3 + 3 = 6, but in music theory, 3rd + 3rd = 5th >:(

Six: Does Not Compute

Seven: Probably Wrong

• 167: The Penney Ante: for any series of three ordered Heads or Tails in a sequence of coin flips, you can choose another one ordered series that is more likely to come up earlier in the sequence
• 168: James Grime’s nontransitive dice: five dice, each numbered differently, which form a cycle of the likelihood of one die having a higher roll than the other

Eight: Put Your Money Where Your Mistakes Are

• 217: Daylight savings time: it’s true that heart attacks are more common than average on days when we lose an hour, and less common than average on days when we gain an hour. But if we look at weeks when we lose an hour, heart attacks are no more common than the average week (and similar for weeks when we gain an hour). Conclusion: People who were on the brink of having a heart attack will have it on the day they lose an hour of sleep, but DST doesn’t cause people who weren’t about to have a heart attack to have heart attacks

9.49: Too Small to Notice

Ten: Units, Conventions, and Why Can’t We All Just Get Along?

• 237: Frigorific mixture: combination of substances that, when mixed, will move towards a fixed temperature.
  • Ice and water will balance at 32ºF by definition, while ammonium chloride, water and ice will balance at 0ºF (at least originally - the scale is now fixed by the melting and boiling points of water).

Eleven: Stats the Way I Like It

Twelve: Tltloay Rodanm

Thirteen: Does Not Compute

• 316: website error codes: if it starts with a 4, the error is on the user’s end; if it starts with a 5, it’s on the server’s end

So, What Have We Learned From Our Mistakes?

• 324: “Mathematicians aren’t people who find math easy; they’re people who enjoy how hard it is.”