an attempt to extort money from the Professor. However, after the Professor writes down Euler's formula during this confrontation, the Widow immediately comes to accept the Housekeeper and Root. She cannot walk well, which the Housekeeper later discovers was a result of her being in the same auto accident as the Professor. While browsing through the Professor's baseball card collection in the cookie tin, the Housekeeper discovers an old photograph of a younger Professor and his sister-in-law. It is hinted that perhaps long ago the Professor and his sister-in-law once had romantic feelings for each other. Mathematical terminology that occurs in the story root imaginary number factorial amicable number prime number twin prime perfect number abundant number deficient number triangular number Ruth-Aaron pair Mersenne prime Napier's constant Euler's formula Fermat's Last Theorem Artin's conjecture Film A film based on the novel was released on January 21, 2006. It was directed by Takashi Koizumi. In contrast to the original work, which is told from the perspective of the narrator, the film is shown from the perspective of 29-year-old "Root" as he recounts his memories of the Professor to a group of new pupils. Though there are a few differences between the film and the original work (for example, the movie touches on the relationship between the Professor and the widow, while the book does not give much detail), the film is generally faithful to the original. Notes and references 2003 Japanese novels Japanese novels adapted into films Shinchosha books Novels by Yōko Ogawa