This book is sort of a charming portrait of a little pseudo-family, consisting of a professor, a housekeeper, her son, and the professor’s sister-in-law. For the most part it’s a relatively calm and placid storyline, with relatively little drama aside from the daily ebb-and-flow of life. The professor and the housekeeper’s son form a bond around baseball and their shared love of the Hanshin Tigers. The housekeeper and her son both pick up more than a little mathematical insight from the professor - one of the main plot points is their arduous search for Gauss’s formula for the sum of integers. The professor, whose once-promising career in mathematics was cut short by a 1975 car crash which rendered him unable to form new memories, becomes a close friend of the housekeeper and her son. And the sister-in-law lurks in the background, for the most part very secretively.

I must confess that the mathematical meaning was a little lost on me, at least until I read this \2. I had not really thought about the “family of numbers” analysis of Euler’s identity as it related to the storyline, but this take on the book is certainly illuminating, and worth a read in its own right.

What was somewhat interesting to me was the little digression into the proof of Fermat’s Last Theorem towards the end. Andrew Wiles provided a general proof for the theorem in 1993, based in part on the Taniyama–Shimura conjecture. Is the professor in this book meant to be a kind of doppelganger for Taniyama or Shimura? It’s unclear to me, since his life circumstances don’t really match those of either earlier mathematician. It seems to be implied, though.

On the whole I enjoyed the book. It’s a little off-beat but certainly thought-provoking and worth a read.