As a Mandarin slang term, 250 (二百五 pinyin èrbǎiwǔ) is an insult meaning "stupid person" or "simpleton". The expression is based on bàndiàozi (半弔子 or 半吊子). In ancient China, copper coins were grouped by stringing them together through the square holes in the center; originally 1000 was a unit of currency called a diao. Ban diao zi literally means half a diao (500 coins). Since modest Chinese scholars may call themselves ban diao zi to humbly deprecate their own expertise, ban diao zi is not necessarily a pejorative term. On the other hand, Er bai wu (250) is half of a ban diao zi and it is an insult.

Two hundred [and] fifty is also:

251 has its own article

252 has its own article

253 has its own article

254 =&nbsp 2 ·127, semiprime, nontotient

255 has its own article

256 has its own article

257 has its own article

258 has its own article

259 has its own article

...
Wikipedia