I'm speculating when I say that I think all these USES are using the word number where the sense of "thing" applies: a hot thing, rolling a thing, doing a thing.

我推想，在这些用法里，凡是出现number的地方都可以用thing来替代而不改变原意，比如：a hot thing, rolling a thing, doing a thing。

youdao

For the present is the only thing of which a man can be deprived, if it is true that this is the only thing which he has, and that a man cannot lose a thing if he has it not.

如果这是真的，即一个人只拥有现在，那么一个人就不可能丧失一件他并不拥有的东西。

youdao

His name was never in the papers. But he's a human being, and a terrible thing is happening to him.

VOA: special.2009.11.29

Any right-thinking printer or any right-thinking publisher would scoff at the presumption of a poet who demanded such a thing.

任何一个思想健全的印刷商和出版商,都会嘲笑你去假定诗人需要这样的东西。

耶鲁公开课 - 弥尔顿课程节选

A person, a place or a thing that's related to something that you're talking about in the present moment.

你可以谈论与当前的情景相关的人物、地点或者事物。

remind me of 课堂 - SpeakingMax英语口语达人

Mr. MARK MOTHERSBAUGH (Devo): (Singing) Everybody needs a good thing, everybody wants a good thing, everybody.

NPR: The '80s Strike Back: Devo's Mark Mothersbaugh

They look at a little thing here, a little thing there, and they keep track of it all.

CNN: Is the Internet the future of community?

Depending on how you look at it, looking like Casey Anthony can be a good thing or a bad thing.

FORBES: Casey Anthony Lookalike Cashing In?