Definition
To prioritize one's own interests and well-being above those of others; to act selfishly.
只顧自己，不顧他人。
In business negotiations, you have to look out for number one; sometimes, you need to be a little selfish.
在商業談判中，你必須為自己著想；有時候，你需要有點自私。
I know we’re a team, but sometimes you have to look out for number one.
我知道我們是一個團隊，但有時候你必須為自己著想。
In a competitive workplace, many people look out for number one.
在競爭激烈的工作場所，很多人只為自己著想。