mordant wit

Autistic savant Daniel Tammet's brilliance with numbers is well known. But, he tells Cassandra Jardine, he's now managing to solve other conundrums

Daniel Tammet locks his eyes on to mine just a shade too long as he opens the door to his home in Herne Bay in Kent. His manner is a trifle stiff.

"Would you like a drink?" he asks, in a voice that lacks expression. But he goes through the social motions with competence, if not ease.

This comes as a relief, for Tammet, now 26, is an autistic savant with prodigious abilities similar to those that Dustin Hoffman portrayed in the film Rain Man. There are only about 50 savants in the world (all men), but Tammet is unique in being able to describe how his mind works.

"I'm lucky," he says, "because most others who have rare abilities are also seriously disabled."

Two years ago, Tammet became famous for reciting pi to 22,514 decimal places with the same ease that the rest of us can reel off 3.142. Even more remarkably, he says he could still do it: his memory is not only extraordinarily capacious, it also retains everything.

In a documentary last year, he again demonstrated his numerical powers, this time by breaking the bank in Las Vegas, never having played blackjack before. And now he has done something that, for a man who describes words as "his second language", is even more remarkable: he has written a book.