Page "Japanese wordplay" Paragraph 2

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.