Mnemonics…easy as pi

Pi = 3.1415926535897932384626433832795028841971

Mapping out the digits of pi (the ratio between a circle’s circumference and its diameter) has been a major mathematical challenge ever since the invention of the wheel first stirred a real interest in circles. The earliest recorded values of pi were Phoenician (3 1/8) and Egyptian (3 13/81). Both values are accurate within a half a percent. Pi even appears in several texts in the Bible, assigned a rough empirical value of 3.

Why should you care about knowing the precise value of pi unless you are preparing for a geometry exam (and don’t have access to a calculator)?  For fun, of course!  One gentleman, Hiroyuki Goto, recited no less than 42,000 digits of pi from memory in 1995.  This record feat took him about nine hours to complete. If that challenge seems a little out of your range, you can still impress your friends by memorising a few mnemonics to help you remember the value to the first 30 or so decimal places.

In the following mnemonics, the number of letters in each word corresponds to a digit.

Seven decimal places:
How I wish I could calculate pi.

Fifteen decimal places:
How I wish I could calculate pi.
How I like a drink, alcoholic of course,
after the heavy lectures involving quantum mechanics.

Twenty one decimal places:
Now, I wish I could recollect pi.
“Eureka,” cried the great inventor.
Christmas Pudding; Christmas Pie
Is the problem’s very centre.

Thirty decimal places:
Now I will a rhyme construct
By chosen words the young instruct.
Cunningly devised endeavor,
Con it and remember ever.
Widths of circle here you see.
Sketched out in strange obscurity.

And if you feel the need for a device for remembering thirty one decimal places of pi, try this rhyme:

Sir, I bear a rhyme excelling
In mystic force, and magic spelling
Celestial sprites elucidate
All my own striving can’t relate
Or locate they who can cogitate
And so finally terminate. Finis.

The problem with this type of mnemonic is how to represent the digit zero (which occurs in pi at the thirty second place). Several people have come up with ingenious methods of overcoming this, most commonly using a ten letter word to represent zero. In other cases a certain piece of punctuation indicates a naught.

There are many stories and poems crafted in this way; Near a Raven, is a poem which currently holds the record for the longest pi mnemonic, at 740 digits. Cadaeic Cadenza is a short story which is longer still at 3835 decimal places, and has additional constraints.

And you thought you would be bored this weekend…

You can read more Lighter Side articles by Pamela Hellig here.

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