How do you spell 1700-1800s?

The most common way to spell the period between 1700 and 1800 is "the eighteenth century" or "the 18th century".

Here's why:

* Centuries start with the year "1" and end with the year "00". So the 18th century encompasses the years 1701 to 1800.

* "1700-1800s" is technically correct but a bit awkward. It's more common to refer to it as a single century.

If you want to specifically mention the years 1700 to 1800, you could say:

* "The period from 1700 to 1800"

* "The late 1700s and early 1800s"

Remember to be consistent with your terminology throughout your writing.