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Piphilology

Mnemonics of pi's digits

  • 20 min read
  • 4 chapters

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Through Mnemonic, 0 and Rounding

There are many ways to memorize π, including the use of piems (a portmanteau, formed by combining pi and poem), which are poems that represent π in a way such that the length of each word (in letters) represents a digit. An example of a piem is: "Now I need a drink, alcoholic of course, after the heavy lectures involving quantum mechanics." The first word has three letters, the second word has one, the third has four, the fourth has one, the fifth has five, and so on. In longer examples, 10-letter words are used to represent the digit zero, and this rule is extended to handle repeated digits in so-called Pilish writing. The short story "Cadaeic Cadenza" records the first 3,834 digits of π in this manner, and a 10,000-word novel, Not A Wake, has been written accordingly.

However, poems prove to be inefficient for large memorizations of π. Other methods include remembering patterns in the numbers (for instance, the year 1971 appears in the first fifty digits of π) and the method of loci (which has been used to memorize π to 67,890 digits).

History

Until the 20th century, the number of digits of pi which mathematicians had the stamina to calculate by hand remained in the hundreds, so that memorization of all known digits at the time was possible. In 1949 a computer was used to calculate π to 2,000 places, presenting one of the earliest opportunities for a more difficult challenge.

Later computers calculated pi to extraordinary numbers of digits (2.7 trillion as of August 2010), and people began memorizing more and more of the output. The world record for the number of digits memorized has exploded since the mid-1990s, and it stood at 100,000 as of October 2006. The previous record (83,431) was set by the same person (Akira Haraguchi) on July 2, 2005, and the record previous to that (42,195) was held by Hiroyuki Goto. An institution from Germany provides the details of the "Pi World Ranking".

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