Katie Hafner in The New York Times:
This is Daniel Tammet’s unlikely and delightful word choice in describing a conversation about numbers with a woman he was tutoring in mathematics. His student was a homemaker whom he mistrusted at first because her motive for learning math was entirely pragmatic: she wanted to become an accountant. “There seemed to me something almost vulgar in the housewife’s sudden interest in numbers,” he writes, “as if she wanted to befriend them only as some people set out to befriend well-connected people.” Then one day, teacher and student were discussing fractions, and what happens when a number is halved, then halved again. They expressed their shared amazement, “almost in the manner of gossip,” Mr. Tammet writes. “Then she came to a beautiful conclusion about fractions that I shall never forget. She said, ‘There is no such thing that half of it is nothing.’ ” Mr. Tammet, whose previous books are “Born on a Blue Day” and “Embracing the Wide Sky,” is a “prodigious savant” — someone who combines developmental disabilities, in this case autism, with the skills of a prodigy. Happily, unlike many savants, he has a rare ability to describe what he sees in his head. His new book is, in part, a description of an intimate relationship with numbers. Not uncommonly for people with autism, he has the remarkable condition called synesthesia, in which seemingly unrelated senses are combined — so that each number is accompanied by its own unique shape, color, texture and feel. The number 289 he finds hideous, while 333 is very appealing. And pi is a thing of pure beauty. Its trillions upon trillions of digits speak to Mr. Tammet of “endless possibility, illimitable adventure.” (This is something we have been able to appreciate only in recent history: Archimedes knew pi to only three correct places, and Newton went only 13 places beyond that.)
For Mr. Tammet, the adventure culminated on March 14, 2004 — Pi Day, of course — when he recited pi from memory, to 22,514 places, over a period of five hours and nine minutes, to a packed room of spectators in Oxford, England. His description of the shape and character the digits took as they rolled across his brain, past his tongue and out his mouth, is at once eerie and poetic. In the course of his recitation, he writes, the audience sat quietly, deeply moved.
More here.