The Big Book of PiThe Famous Number You Can Never Know
Review posted April 7, 2026.
Helvetiq Publishing, 2026. First published in Switzerland.
Review written March 31, 2026, from a library book.
Starred Review
How much do I love that this book exists? An uncountable quantity! This book is a kid-friendly look at the number pi. It gives a basic explanation of pi, the history of pi and how it gets used, including lots of people who developed the concept. It explains pi's relationship with circles, the concept of irrational numbers, explores the implications of infinite digits, and how pi has been calculated over the years. And of course the history of people reciting digits of pi. It finishes up with practical tricks you can do to amaze your friends using pi.
And throughout, things are kept light with plenty of pi puns and cartoon illustrations. The illustrations help explain the concepts, and it's all written at a level that an upper elementary school or middle school student can understand. Budding math geeks will love it!
And yes, I learned things about the history of pi - like the guy who thought he'd calculated pi to 707 digits, but it was discovered after his death that every number after the 527th was incorrect. Or that two pairs of brothers, one pair in Scotland and one pair in Ukraine, simultaneously worked on Ramanujan's formula to each independently create the same new, even better formula for calculating more digits of pi.
I also didn't know that before William Jones started using the Greek letter pi for this quantity, it was known as: "The quantity which, when the diameter is multiplied by it, yields the circumference" - except in Latin.
Lots of cool math facts to be found here! Try putting it in front of your own kid and see if it doesn't pull them in.