Pi Day: five fun facts about 3.14

March 14, or 3.14, is Pi Day. Get it? Pi Day celebrates all things related to the mathematical constant that measures the ratio of a circle's circumference to its diameter. Here are five things you should know about π. 

3. It has stretched the bounds of the human mind

Sure, a computer can calculate trillions of pi’s decimals, but what about the human mind?

The current pi memory champion is a retired Japanese engineer Akira Haraguchi, who in 2006 recited 100,000 digits in front of witnesses in Tokyo. The event took nearly 17 hours. Previously, Mr. Haraguchi set three earlier records by reciting 54,000 digits in September 2004, 68,000 digits in December 2004, and 83,431 in July 2005. To date, however, the Guinness Book of World Records has not officially verified Haraguchi’s attempts.

The current Guinness-record holder for memorized digits of pi is held by Lu Chao, a 24-year-old student from China, who recited 67,890 digits in 24 hours and four minutes. 

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