"What's 81 to the power of four?" I ask Rüdiger Gamm, coming up with a sum I deem perplexing enough to stump my interview subject's reputed mathematical genius.
Gamm pauses for no more than two seconds before delivering his answer from his home in Welzheim, Germany: "Forty-three million, 46 thousand, 721."
I follow up with another question: "OK, 27 to the power of six?"
"That would be 387,420,489," he swiftly replies.
While I am equipped with a calculator, Gamm is - at least I assume so, considering our geographical separation - using nothing but his powerful and agile mind to solve these complex arithmetical conundrums. He is a calculating prodigy, possessing an astounding mind that can multiply and divide huge numbers.
Such is the 40-year-old German's capacious brainpower that he's a minor celebrity in his mother country and considered something of a scientific wonder elsewhere.
Gamm makes a decent living by coaching businesspeople and students to improve their memory and concentration skills. He's also active on the seminar circuit, where he shows off the full might of his remarkable mind. In both of these capacities, Gamm will be visiting the Emirates later this month for an event in Dubai.
But life has not always been easy for Gamm - far from it. Surprisingly, he was an underachiever at school, he found himself frequently bored in lessons and often felt uninspired by his teachers.
"I was the worst in my class at maths," states Gamm, "I failed my exams six times.
"I hated school a lot. The only thing I was interested in was bodybuilding. I wanted to be Arnold Schwarzenegger, rather than a mathematician."
Gamm's responses arrive in the form of precise statements that puncture our crackly intercontinental phone line. They are quick-fire sentences delivered in an impassive tone, which perhaps goes some way towards explaining why his genius may have been left undisturbed by his educators. It was only when he became unbound from the constraints of school and university that his mediocrity came to an abrupt conclusion.
"I discovered my ability about two weeks after I left college at the age of 21," he recalls.
"I was listening to the radio, and there was a champion mathematician on the show doing some calculating. They kept asking him questions and I realised I could answer quicker than him.
"I knew I had a good memory for numbers, but I didn't know I could do these large sums. I guess I had never thought to try it [before then]."
By applying the same discipline to training his mind as he had to pumping iron, a year later in 1994, confident of his mathematical prowess, he volunteered to be a contestant on the popular German TV game show, Wetten, dass?, better known in the US as Wanna Bet? and in the UK as You Bet!
Gamm says: "It was amazing. I won the show with the highest score ever. My prize was 8,400 Deutsche Marks [worth approximately US$13,600 in the mid-Nineties], because I had achieved 84 per cent of the score. This was the highest score ever."
Fame was his, at least in Germany, and soon word of his amazing talent spread far and wide, as neurologists from across the world sought to study the anomalies of his mind.
"The scientists wanted to know if my brain worked in the same way as other people, so I had a lot of tests with a head scanner," he states. "They discovered that I calculate with the right hemisphere of my brain. Usually you calculate with the left hemisphere, so this means that I use the part of the brain other people use for other things.
"When results of my brain scans were published it helped make me famous all over the world."
Essentially, the scientists concluded that somehow he had rewired his brain to unlock its hidden potential. Whereas most of us only utilise 20 per cent of our mental capacity, Gamm could employ up to 80 per cent of his.
Although intelligence is particularly hard to quantify, in the most commonly accepted form of assessment, Gamm was found to have an IQ somewhere in the region of 200. The subject himself was sceptical about these results.
"This result was from an IQ test I had in Belgium in the 1990s. But you must be very careful about this, as it was just a suggestion. I recently did two tests on the internet, and in one I had an IQ of 173 and the other one I had an IQ of about 92. So it depends on the test. If you live in a small village in Africa, you cannot do these kind of tasks. But we cannot make fire, so isn't that a form of intelligence? It's hard to put a number on intelligence."
Gamm was also found to be exceptional in that he was clearly abnormally gifted, yet he exhibited no autism-related neural disorder.
He explains: "There are a lot of people with special abilities or savants, but they usually have handicaps in their normal lives. I've been told that I'm the only savant in the world who is not handicapped in their normal life. As they're usually autistic or have some kind of mental disability, and I don't."
Another renowned savant was Kim Peek, the inspiration for Raymond Babbitt, the intractable character played by Dustin Hoffman in the Oscar-winning movie Rain Man. Peek, who died in 2010, suffered with severe developmental disabilities, but possessed an eidactic memory and could recall word-for-word more than 12,000 books he'd read, yet was unable to dress himself without help or even brush his teeth. Gamm met Peek when they were both guests on a German television chat show in 2006. He says: "He was a very interesting character, but he needed help with his own life. I could not understand or connect with him. You couldn't talk to him in a normal way."
And Gamm insists his abilities are not the results of any autistic condition.
"Apart from my mathematical ability, I think I am normal," he insists. "I have a girlfriend called Alexandra. We've been together for eight years, and known each other for 20, so we have a perfectly normal life."
So, does his otherwise averageness give hope that the rest of us could train ourselves to attain his level of intellectual acumen?
"I don't think so," he replies with typical bluntness. "Everyone is born with their own talent, it's just a matter of discovering it and nurturing it. Almost everyone who comes to my seminars should be able to improve their mental capabilities if they pay attention. It is possible I will find a mental calculator of [equal] ability in Dubai, but who knows?
"But I was born with this talent. Other people can train their brains and become better, but they cannot become the best in the world unless they have a natural talent."
Which means, for now, I'll be sticking with my trusty Casio calculator.
BOLDTalks take place at Dubai Community Theatre and Arts Centre on February 25 at 10am. Tickets cost Dh200. For more information, call 04 441 6216 or visit www.boldtalks.com.