A man from Kent has set a new British and European record by reciting the mathematical expression pi to more than 22,000 decimal places.
Daniel said he remembered the number backwards and forwards
Daniel Tammet, 25, from Herne Bay, puts his ability to recall such a vast quantity of figures down to epileptic seizures he had during his childhood.
He used his record-breaking feat, which took nearly six hours, to raise money for the National Society for Epilepsy.
He said learning the number was "actually rather easy".
Pi is the mathematical term for the ratio of the circumference of a circle to its diameter - 3.14, to two decimal places.
Mr Tammet went 15 decimal places beyond the existing British and European record set by a David Thomas in 1998.
He performed the feat on Sunday before an audience at Oxford University's Museum of the History of Science, sitting in front of a blackboard once used by Albert Einstein.
Mr Tammet, who also speaks several languages, is recognised as a "savant" - one of a small group of people capable of extraordinary mental feats linked to a medical condition.
US expert Dr Darold Treffert has listed just 25 savants in the world.
Upsides and downsides
Dr Treffert was consulted during the making of the film Rain Man, in which Dustin Hoffman played an autistic savant.
Mr Tammet said the record attempt was like "running a marathon in your head" and that the hardest part was sitting still for so long.
He said: "It literally took me a few weeks to learn the number, and that was backwards as well as forwards, it wasn't a problem for me at all.
"I would even go so far as to say it was actually rather easy."
Dustin Hoffman raised awareness of savants in the film Rain Man
Mr Tammet admitted his condition had made tasks like learning to swim, ride a bike or drive a car "very difficult".
He said: "There are upsides as well as downsides.
"The upsides are that I don't have to carry lots of things around with me, I don't have an address book and I don't carry a telephone book."
The National Society for Epilepsy (NSE) is now set to submit proof of the feat to the Guinness Book of Records for it to be confirmed as a record.
The charity plans to use money raised at the event to fund an information leaflet on epilepsy and memory.
An NSE spokesman said: "The record-breaking challenge has given out a very positive message about epilepsy - the condition doesn't need to affect someone's ability to use their brain, nor stop them aspiring to great achievements."
Mr Tammet plans to visit the US in the next few weeks to meet Dr Treffert and other savants, having never met anyone else with the condition before.
The world record of 42,195 decimal places was set in 1995 by Hiroyuki Goto from Tokyo.