If you are writing a formal paper, how do you write 1600s (as in the century)? Is there an apostrophe: 1600's?

Thank you for using the Jiskha Homework Help Forum. This is what the MLA guide says concerning dates:

Full dates when written in the text may be in US format: month day, year (e.g., August 21, 2001); or in universal or European format, day month year (e.g., 21 August 2001). MLA style requires universal format when writing dates in references so it makes sense to extend this practice to the text as well. Whatever format you select be consistent throughout the text.

You could also look in your History book and/or literature to see what you find there.

The correct form is 1800s -- without an apostrophe.

http://www.bartleby.com/68/21/1621.html

thanks!