## how to memorize pi -- 6/20/18

**Today's selection -- from The Magic of Math by Arthur Benjamin.** Fun with π:

"The number π has developed almost a cult following. Many people like to celebrate the number π on Pi Day, March 14 (with numeric representation 3/14), which also happens to be the birthdate of Albert Einstein. A typical Pi Day event might consist of mathematically themed pies for display and consumption, Einstein costumes, and of course π memorization contests. Students generally memorize dozens of digits of π, and it is not unusual for the winner to have memorized over a hundred digits. By the way, the current world record for π memorization belongs to Chao Lu of China, who in 2005 recited π to 67,890 decimal places! According to the *Guinness Book of World Records*, Lu practiced for four years to reach this many digits, and it took him a little over twenty-four hours to recite all the digits.

"Behold the first 100 digits of π:

π = 3.141592653589793238462643383279502884197169399375 105820974944592307816406286208998628034825342117067 ...

Leonhard Euler popularized the use of the Greek letter π in works he published in 1736 and 1748. |

"Over the years, people have come up with creative ways to memorize the digits of π. One method is to create sentences where the length of each word gives us the next digit of π. Some famous examples include 'How I wish I could calculate pi' (which yields seven digits: 3.141592) and 'How I want a drink, alcoholic of course, after the heavy lectures involving quantum mechanics' (which provides fifteen digits).

"A most impressive example was written in 1995 by Mike Keith, who generated 740 digits in an amazing parody of Edgar Allan Poe's poem 'The Raven.' The first stanza, along with the title, generates 42 digits. The stanza's 'disturbing' ten-letter word generates the digit 0.

Poe, E. Near a Raven

Midnights so dreary, tired and weary.

Silently pondering volumes extolling all by-now obsolete lore.

During my rather long nap -- the weirdest tap!

An ominous vibrating sound disturbing my chamber's antedoor.

'This,' I whispered quietly, 'I ignore.'

"Keith went on to extend this masterpiece by writing a 3835-digit 'Cadaeic Cadenza.' (Note that if you replace C with 3, A with l, D with 4, and so on, then 'cadaeic' becomes 3141593.) It begins with the 'Raven' parody, but also includes digital commentaries and parodies of other poems such as Lewis Carroll's 'Jabberwocky.' His most recent contribution to this genre is *Not a Wake: A Dream Embodying π's Digits Fully for 10000 Decimals*. (Note the word lengths in the book's title!) ...

"The phonetic code is quite useful for memorizing dates, phone numbers, credit card numbers, and more. Try it, and with a little bit of practice, you will vastly improve your ability to remember numbers."

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