Nancy’s question: “I have a question regarding the use of the apostrophe after dates and acronyms. It used to be standard, but I’ve noticed some lapses lately, e.g., 1900′s is now 1900s, and she grew up in the 80′s is now she grew up in the 80s. And what about plural acronyms? LED’s are the new light source is now LEDs are the new light source. What is correct?”
BizWritingTip response: This is an area that causes a lot of confusion. Apostrophes are used to show possession or to indicate a missing letter(s) or number(s). I am not sure why people would insert an apostrophe when a word, acronym, or number is merely plural.
For instance, if I wrote she grew up in the ‘80s, there is no need for an apostrophe after the number as there is no possession or missing letters implied. It is simply plural. (There is an apostrophe before the number to indicate the missing 19.)
I am glad I did not live in the 1900s.
My grandparents came to this country in the early ‘60s.
The same rule holds for the plurals of capital letters.
Correct (when the abbreviation is simply plural)
Did you find the CDs?
LEDs are the new light source.
There are three MDs in the building.
Correct (when the abbreviation is plural and possessive)
Did you find the five CDs’ cases?
There are three MDs’ offices in the building.
Correct (when the abbreviation is singular and possessive)
Did you find the CD’s case?
There is an MD’s office in the building.
Exception: Use an apostrophe with an initialism, if the meaning would be unclear without it.
Please cross your t’s. (Ts would look like a typo.)
Mind your p’s and q’s.
Getting A’s in the course is difficult.