Excessive apostrophe use is one of the most frequent conditions affecting writers today. How would you like it if a dash were to float above your head, looming over you all day long? Well your numbers and letters don’t like it either. In fact the Chicago Manual of Style says that the use of apostrophes is unnecessary when referring to multiple numbers or letters. So 7’s becomes 7s and D’s becomes Ds. This rule also applies to decades, 1920’s should be written as 1920s.
Also, keep in mind that an apostrophe does not always make something possessive. The word “its” is a possessive pronoun, though “it’s” (it is) is often mistakenly used instead. Confusing these words is a common grammatical error and may not be caught by some spell checkers. Remember these new rules about apostrophes, so the next time you write “the 80s called, it wants its jacket back,” you can look funny and smart!