Gregorian calendar year to Japanese era name, and vice versa


Just for fun, I'm curious about how native speakers do mental translation from
Gregorian calendar year (e.g 2011) to Japanese era name 年号 (e.g. 平成２３年), and
vice versa. Do you have special and preferably fun ways like mnemonics or
children songs (something like the ABC song) to help you do the translation
on-the-fly?

p/s: Due to subjectiveness of this question, I'm totally fine if this is made
into community wiki.




From experience, I find Japanese people having lots of trouble converting
between Japanese and Gregorian calendar years. I regularly surprise people
with my ability to do that as follows (Japanese calendar years are often
represented with an alphabet character like `S` or `H`.):

**Showa Era (1925 to 1989)**

  1. Subtract 1900 (e.g. 1976 - 1900 = 76)
  2. Subtract 25 (e.g. 76 - 25 = S 51)

**Heisei Era (1989 to 2000)**

  1. Count forward from 1989 (e.g. 1989 = H1, 1990 = H2, ...)

**Heisei Era (2000 onwards)**

  1. Add 11 to post-2000 Western date (e.g. 2010 = H21, 2011 = H22, ...)

