The mathematician was a number theorist, and though he cannot form any new memories following the car accident, he still remembers detailed information about the integers and their properties. For instance, each time the housekeeper arrives it is as if he is meeting her for the first time. He always asks her to name some number from her life (e.g. phone number, age, etc.) and will then tell her what makes that number special.

In addition to a lot of number theory, the novel includes many references to baseball, a few references to religion and some significant references to Euler's formula relating e, π, i, 1 and 0 (although in my copy of the book the equal sign was missing from the equation each time it appeared).

This is a really sweet novel in which the reader not only gets to appreciate mathematics through the eyes of the nameless housekeeper, but also gets to like the people. Just as the housekeeper missed the professor during the brief period when she lost her job working for him, I miss all of the characters in the book now that I have finished reading it. It is not a "page turner"; there is no mystery or conflict that drives the plot. We merely share some time with these likable characters and learn about those things that give their lives meaning and purpose.

Note Added January 2009: This book has now been translated into English by Stephen Snyder (a Middlebury College Japanese professor) and published by Picador USA under the title The Housekeeper and the Professor. The publisher wrote me to say:

In scenes which were added for the film version (released in 2006), we see "Root" as an adult. He has become a mathematics teacher. His love for mathematics and respect for the old scholar are apparent to the students in the class and supposedly make this an especially touching scene for educators.