- Use an apostrophe to signal plural forms of individual letters of the alphabet and to signal the plural of a word as a word (which should also be italicized).
- Do not use an apostrophe to signal plural numbers or acronyms.
The professor must have used one hundred ah's and uh's during his lecture.
I had two F's on my report card.
There are fifty-two PCs in the accounting department.
An example of four-of-a-kind in a poker hand would be four 9s.
Using apostrophes to signal missing letters
Use an apostrophe to signal missing letters, formal or informal, modern or archaic.
- I can't understand a word you're saying. (cannot, you are)
- 'Twas the eve of his wedding. (It was)
- O'er the mountains yonder. (Over)
Using apostrophes to show possession
- Never use an apostrophe with a pronoun (his, hers, theirs, ours, etc).
- It was his turn to throw the ball.
- That house is theirs.
- The players' locker room was located beneath the stadium.
- The octopuses' tank at the aquarium is very popular. (More than one octopus in a single tank)
- That is James's book.
- The octopus's tank at the aquarium is very popular. (A single octopus in a single tank).