748: "七四八" In Mandarin this number is pronounced "qī sì bā". If these numbers are stated in certain tones, it has a meaning which roughly translates into: "Why don't you go die?" "去死吧" This combination is more commonly used as an insult to others, or rather, an indirect death threat. Youngsters can jokingly tease each other by saying "你去死吧!". Depending on the mood, place and way of saying this sentence it can confer meanings ranging from joking to insulting or provoking. On the other hand, any 3 digit number that ends with 48 sounds like "wealthy for X lifetimes" (世發) (e.g. 748[七世發] is wealthy for 7 lifetimes"), thus is generally considered lucky, with 448 and 548 being the exceptions since they are also homophones of "死先發"(Wealthy on death) and "唔洗發"(no need/not going to be wealthy).