百发百中 one hundred shots, one hundred hits
Explanation
这个成语的意思是形容射箭或打枪准确，每次都命中目标。也比喻做事有充分把握，形容十分有把握，一定能成功。
This idiom describes someone who hits the target every time when shooting arrows or guns. It can also be used to describe someone who has complete confidence in their ability to do something.
Origin Story
春秋时期，楚国名将养由基跟随楚共王出兵援助郑国，楚共王要养由基用两枝箭射死晋国国君魏武，养由基一箭就结束。同行潘党不服，养由基三箭分别射中他们约定百步之外的三片杨树叶，让人不得不佩服。
In the Spring and Autumn period, the famous general Yang Youji from the state of Chu followed King Gong of Chu to help the kingdom of Zheng. King Gong of Chu ordered Yang Youji to kill the ruler of the state of Jin, Wei Wu, with two arrows. Yang Youji finished it with a single arrow. A companion, Pan Dang, was not convinced, whereupon Yang Youji fired three arrows, each hitting a leaf on three different willows, which they had agreed on in a hundred steps. The people could not admire his skills enough.
Usage
百发百中多用于形容射箭或打枪的准确性，也比喻做事情有充分把握，信心十足。
The idiom '百发百中' is often used to describe the accuracy of archery or shooting, and also to describe having complete confidence in one's ability to do something.
Examples
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他的射箭技术非常高超，百发百中。
ta de she jian ji shu fei chang gao chao, bai fa bai zhong.
His archery skills are superb, he hits the target every time.
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这个计划经过周密的考虑，相信会百发百中。
zhe ge ji hua jing guo zhou mi de kao lv, xiang xin hui bai fa bai zhong.
This plan has been carefully considered and is sure to be successful.