肆

numeral: four (formal/financial numeral, used to prevent forgery)
肆

2 candidate readings from Wiktionary — genuine Chaozhou colloquial form not yet confirmed by a speaker. The dossier ties si3 only to this alt-of-四 numeral sense, so this headword was split into sense-specific entries; the other 肆 sense (shop/impudent) is drafted separately with only se3.