Also known as: 語呂合わせ
A system where numbers are used to spell out Japanese words. For example, the number 39 can be read as san-kyuu, which sounds like Thank You in English.
Numbers may be read as native Japanese (kun'yomi), Sino-Japanese (on'yomi), or as English, and are usually shortened to the first kana. They can also be read as though they had dakuten (゛) or handakuten (゜) added to them if necessary. E.g. the number 8 can be ya (short for yattsu), ha (short for hachi), ba (ha with dakuten) or pa (ha with handakuten).