Thousand or Thousands

I am confused at when we should use thousand or thousands. Is "more than eighty thousands" is right? We can not add "s" after "thousand" in this sentence, can we?

[Wai_Wai]

This passage answers nearly the same thing as what you want:

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Hundred VS hundreds

You can try to understand in the following way.

Hundred here is used as if it is an adjective.
So it is non-sense to add a "s" to hundred.
Thus it should be "5 hundred"

Eg:
- There are 5 hundred people in the street. (5 hundred is like an adjective to
describe the no. of people in the street)

However if "hundred is used as a noun, it can be plural. Eg:
- The birthday cake has a large "hundred" on top of it.

NB: Don't mix up with the following
- I spent several hundreds of dollars on clothing. [Since hundred is used as a
noun here, "s" is required]