As a child I came aross a book on memory, which claimed the following poem is a mnemonic for memorizing the first 20 digits of pi:
I wish I could remember pi, "Eureka!" cried the great inventor, Christmas pudding, Christmas pie, Is the problem's very center.
The idea is to take the number of letters in each word. But this is incorrect: the fifth words should be 9 letters long, not 8. I suggest replacing “remember” with “recollect” or “calculate”.
A somewhat self-referential mnemonic for the reciprocal of pi (0.318310…): “Can I remember the reciprocal?”
Despite the ingenuity of these schemes, I later found it easier to group the digits in several chunks, and remember each chunk just as I would do for a telephone number.