When I multiply numbers together, I see two shapes. The image starts to change and evolve, and a third shape emerges. That's the answer. It's mental imagery. It's like maths without having to think.

The human brain is like a memory system that records every thing that happens to us and makes intelligent predictions based on those experiences.

When I achieved the European record for reciting pi in 2004, this captured the imagination of Professor Simon Baron-Cohen in Cambridge and he finally diagnosed me with Asperger's that year.

Why learn a number like pi to so many decimal places? The answer I gave then as I do now is that pi is for me an extremely beautiful and utterly unique thing. Like the Mona Lisa or a Mozart symphony, pi is its own reason for loving it.

My autism is a very mild form. It was diagnosed at the age of 25, partly because it wasn't diagnosable as a teenager (this is Asperger's syndrome, specifically). But there were certainly traits within that condition, within the autism spectrum in general, especially at the high functioning end, that I think are best looked at as pluses.

I certainly have routines in my day-to-day life that are important to me and still give me feelings of security and control, but the capacity to break out of them every so often as I travel has given me a second wind.

Fischer, the great American chess champion, famously said, 'Chess is life.' I would say, 'Pi is life.'