Japanese wordplay  Japanese wordplay relies on the nuances of the Japanese language and Japanese script for humorous effect. Japanese double entendres have a rich history in Japanese entertainment, because of the way that Japanese words can be read to have several different meanings and pronunciations (homographs). Also, several different spellings for any pronunciation and wildly differing meanings (homophones). Often replacing one spelling with another (homonyms) can give a new meaning to phrases.   is an especially common form of Japanese wordplay whereby homophonous words are associated with a given series of letters, numbers or symbols, in order to associate a new meaning with that series. The new words can be used to express a superstition about certain letters or numbers. More commonly, however, "goroawase" is used as a mnemonic technique, especially in the memorization of numbers such as dates in history, scientific constants and phone numbers. Every digit has a set of possible phonetic values, due to the variety of valid Japanese ("kun'yomi" and "on'yomi"), and English-origin pronunciations for numbers in Japanese. Often readings are created by taking the standard reading and retaining only the first syllable (for example "roku" becomes "ro"). "Goroawase" substitutions are well known as mnemonics, notably in the selection of memorable telephone numbers for commercial services, and in the memorization of numbers such as years in the study of history. Mnemonics are formed by selecting a suitable reading for a given number; the tables below list the most common readings, though other readings are also possible. Variants of readings may be produced through consonant voicing or gemination, vowel lengthening, and the insertion of the nasal mora "n" ().  1492 (the year of discovery of America) can be memorized as: "iyo! kuni ga mieta!" (derived as follows: "i" (1) "yo" (4)! "ku" (9) "ni" (2) "(ga mieta)!"), meaning: "Wow! I can see land!" or "i" (1) "yo" (4)! "ku" (9) "ni" (2), "It's good country". Alternately, it can be read as "i"(1)"shi"(4)ku(9)"ni"(2) which has no meaning but is used to memorize the year.  23564 (23 hours, 56 minutes, 4 seconds, the length of a sidereal day) can be read "ni-san-go-ro-shi", which sounds very similar to "nii-san koroshi" (), or in English "killing one's older brother".  3.14159265 (Pi) can be read "san-i-shi-i-ko-ku-ni-mu-kou" (), meaning "An obstetrician faces towards a foreign country."