Akira Haraguchi, of Kisarazu, Chiba Prefecture, is a world-class athlete, and in his particular sport he is the best in the world. You might be puzzled if you saw him: He’s 72, a retired engineer and doesn’t look like a reigning world champion. But his sport is played in the mind, and Haraguchi’s mind is trained to the very highest level. He is a memory athlete.

In 2006, Haraguchi recited the mathematical constant pi to 100,000 digits, in a feat that lasted more than 16 hours. Pi, of course, is the ratio of a circle’s circumference to its diameter, and is an infinite and irrational number. That means it goes on forever, with no repeating patterns of numbers.

To Haraguchi, pi represents a religious quest for meaning. “Reciting pi’s digits has the same meaning as chanting the Buddhist mantra and meditating,” he says. “Everything that circles around carries the spirit of the Buddha. I think pi is the ultimate example of that.”

He spends an hour a day reciting the numbers. He is the world champion, although Guinness World Records has not recognized his recitation. Since the 2006 breakthrough, he has posted videos of himself reciting yet more of pi. His current record is 111,700.

The official Guinness record holder is 23-year-old Rajveer Meena from Sawai Madhopur district in Rajasthan, India. On March 21, 2015, at the Vellore Institute of Technology in Tamil Nadu, Meena recited pi to 70,000 decimal places. He was blindfolded. The feat took him nine hours and seven minutes. One of the factors motivating him, he told me, was his upbringing. He wanted to show that despite his humble background, he could win the world’s toughest memory challenge.

These memory wizards have different motivations, and use different techniques, but they all essentially convert the numbers into a story. When they tell the story in their heads,they translate it back into digits and recite the numbers. It’s a technique anyone can learn, should you want to become a memory athlete.

Haraguchi’s system is based on the Japanese kana alphabet. The first fifty digits of his system read (translated into English): “Well, I, that fragile being who left my hometown to find peace of mind, am going to die in the dark corners; it’s easy to die, but I stay positive.” One hopes that in the rest of the 100,000 digits the story picks up a bit.

For the memory chapter in my book “Superhuman,” I wanted to understand the people, like Haraguchi, who memorize pi, and I felt like I ought to get to know the number a bit better than the first few digits that I know, 3.14159. So I spent some time scrolling through a web page listing pi to 1 billion digits. It’s a mesmerizing experience. I scrolled down steadily for some time, and the scroll marker in the margin was still only about 5 percent of the way down the page.

I felt my mind could unravel if I did this for too long. The tumbling numbers recalled “The Matrix,” but obviously I couldn’t see anything in them, because there isn’t anything in them. Pi is infinite, and so far has been calculated to 22 trillion digits. No one has (yet?) posted this number online.

Haraguchi finds spiritual value in his endeavors. But he has another motivation: to improve human cognition. There’s another chapter in my book that’s on longevity, and as I write, a few weeks ago the then-oldest person in the world died. On April 21, Nabi Tajima died in Kikai, Kagoshima, at the age of 117 years and 260 days. She was the third-oldest person in human history. As always happens when a person attains great age, they are asked the secret of their longevity. Tajima said it was sleeping soundly and eating delicious food.

Nice. But for most of us it will take more than that. We need to work to keep our minds active. This is now thought to protect against dementia, and it points to another of Haraguchi’s motivations: He wants to develop a method to help people recover from dementia.

There are 47 million people in the world suffering from dementia. In one 10-year study of people over 65, scientists found that a kind of brain training that exercises the memory helped protect against subsequent dementia. Haraguchi might be on to something.

Some people have a natural resistance to the ravages of time. Nabi Tajima was one. She escaped having serious illness her entire life.

Scientists have classed people like Tajima, over 90 but with well-functioning memories, as superagers. When they eventually die and their brains are examined, researchers found that some do indeed display the hallmarks of Alzheimer’s disease, but they hadn’t shown the usual loss of memory.

By studying these people we can start to understand how we can all live to a great age, and do it with our memories, and our minds, intact.

Rowan Hooper is the managing editor of New Scientist magazine. His new book, “Superhuman: Life at the Extremes of Mental and Physical Ability,” is out now. Follow him on Twitter @rowhoop.

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