百不失一　

◎ 百不失一 bǎibùshīyī

(1) [cannot possibly go wrong;not a failure out of a hundred trials;never a failure in many trials] 一百次中也不會失誤一次。形容極有把握,決不會出差錯

從門應(yīng)庭,聽堂室之言,什而失九,如升堂窺室,百不失一。——漢· 王充《論衡》

(2) 又說“百無一失”