The answer to the question from last week's post Happy Sinuous Idiom - A New Year's Quiz is The Major System.
The following is excerpted from the Wikipedia page titled Mnemonic major system:
The Major System (also called the phonetic number system, phonetic mnemonic system, or Herigone's mnemonic system) is a mnemonic technique used to aid in memorizing numbers.
The system works by converting numbers into consonant sounds, then into words by adding vowels. The system works on the principle that images can be remembered more easily than numbers.
Each numeral is associated with one or more consonants. Vowels and the consonants w, h, y and x are ignored. These can be used as "fillers" to make sensible words from the resulting consonant sequences. The most popular mapping is:
|0||s, z, soft c||"z" is the first letter of zero. The other letters have a similar sound.|
|1||t, d||t & d have one downstroke and sound similar (some variant systems include "th")|
|2||n||n has two downstrokes|
|3||m||M has three downstrokes and looks like a "3" on its side|
|4||r||last letter of four, also 4 and R are almost mirror images of each other|
|5||l||L is the Roman Numeral for 50|
|6||sh, j, soft "ch", dg, zh, soft "g"||a script j has a lower loop / g is almost a 6 rotated|
|7||k, hard c, hard g, hard "ch", q, qu||capital K "contains" two sevens (some variant systems include "ng")|
|8||f, v||script f resembles a figure-8. V sounds similar.|
|9||p, b||p is a mirror-image 9. b sounds similar and resembles a 9 rolled around|
|Unassigned||Vowel sounds, w,h,y,x||These can be used anywhere without changing a word's number value|
Each numeral maps to a set of similar sounds with similar mouth and tongue positions. The link is phonetic, that is to say, it is the consonant sounds that matter, not the spelling. Therefore a word like action would encode the number 762 (k-ch-n), not 712 (k-t-n); and ghost would be 701 (g-z-t), while, because the gh in enough is pronounced like an f, the word enough encodes the number 28 (n-f). Similarly, double letters are disregarded. The word missile is mapped to 305 (m-z-l), not 3005 (m-z-z-l). To encode 3005 one would use something like mossy sail. Often the mapping is compact. Hindquarters, for example, translates unambiguously to 2174140 (n-d-qu-r-t-r-z), which amounts to 7 digits encoded by 8 letters, and can be easily visualized.
I learned about the Major System while reading the book Fooling Houdini by Alex Stone. This outstanding, non-fiction book is subtitled: Magicians, Mentalists, Math Geeks and the Hidden Powers of the Mind. I highly recommend it to geeks and non-geeks alike. It is a fascinating and enjoyable read written in a very entertaining and informative style.
For more fun with the Major System check out the Phonetic Mnemonic Major Memory System Database. It contains 32,320 unique keywords for 13,221 numbers.