Akira Haraguchi

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Akira Haraguchi (原口 證, Haraguchi Akira) (born 1946, Miyagi Prefecture), a retired Japanese engineer, is known for memorizing and reciting digits of pi.

Memorization of pi[edit]

He holds the current unofficial world record (100,000 digits) in 16 hours, starting at 9 a.m (16:28 GMT) on October 3, 2006 and having recited up to 83,431 digits by nightfall, stopping with digit number 100,000 at 1:28 a.m. on October 4, 2006. The event was filmed in a public hall in Kisarazu, east of Tokyo, where he had five-minute breaks every two hours to eat onigiri to keep up his energy levels. Even his trips to the toilet were filmed to prove that the exercise was legitimate. Haraguchi's previous world record (83,431), was performed from July 1, 2005, to July 2, 2005. On Pi Day, 2015, he claimed to be able to recite 111,701 digits.[1]

Despite Haraguchi's efforts and detailed documentation, the Guinness World Records have not yet accepted any of his records set.

Haraguchi views the memorization of pi as "the religion of the universe",[2] and as an expression of his lifelong quest for eternal truth.

Haraguchi's mnemonic system[edit]

Haraguchi uses a system he developed, which assigns kana symbols to numbers, allowing for the memorization of Pi as a collection of stories. The same system was developed by C.S. Lewis to assign letters from the alphabet to numbers, and creating stories to memorize numbers. This system preceded the system above which Haraguchi developed.[citation needed]



0 => can be substituted by o, ra, ri, ru, re, ro, wo, on or oh;
1 => can be substituted by a, i, u, e, hi, bi, pi, an, ah, hy, hyan, bya or byan;

The same is done for each number from 2 through 9. His stories are what he used to memorize pi.


  1. ^ a b Bellos, Alex (2015-03-13). "He ate all the pi : Japanese man memorises π to 111,700 digits". The Guardian. Retrieved 2015-08-14.
  2. ^ a b Otake, Tomoko (2006-12-17). "How can anyone remember 100,000 numbers?". The Japan Times. Retrieved 2007-10-27.

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