The Apostrophe with Numbers, Letters, and Abbreviations

Rule 1: The plurals for capital letters and numbers above nine do not require apostrophes, but some use them anyway.

She learned her ABCs.
(some writers prefer ABC’s)
the 1990s (some writers prefer 1990’s)

Rule 2: For clarity, most writers use apostrophes with single capital letters and single-digit numbers.

Please dot your I’s.
She learned her times tables for 6’s and 7’s.

Posted on Monday, November 9, 2009, at 10:28 am

8 Comments on The Apostrophe with Numbers, Letters, and Abbreviations

8 responses to “The Apostrophe with Numbers, Letters, and Abbreviations”

  1. Angela says:

    How about apostrophes to show possessive after abbreviations ending in S? Danish company names mostly end in A/S or ApS (initialisms), so would the correct form be e.g. Trading Company A/S’s sales in 2013… or would you just use an apostrophe without the s?

    • Jane says:

      In this case, we recommend adding ‘s after the name for clarity: A/S’s sales, ApS’s marketing strategy. However, some authorities recommend just an apostrophe after proper nouns, including company names, when they end in the letter s.

  2. Don N. says:

    I love your website. I really do. Your explanations of the convoluted English language, the only language misbegotten by the malconceived marriage between two totally incompatible liguistic familes, are clear and easy to understand. Your examples of correct and incorrect usage are excellent; they’re sentences that real users of English would use, unlike similar examples in some other places.I have taught English in one role or another for well over 40 years, and see a site like yours as invaluable. I am a true believer that the proper use of English grammar and spelling makes communication clearer, that clear communication is necessary for peace, and that, therefore, you’re doing nothing less than serving as a champion for world peace by your excellent work.

    Given that great background, I was shocked to see your advice to people to use apostrophes when pluralizing single letters. This is totally incorrect. The proper way to pluralize single letters and the letters that form acronyms is to capitalize them and follow them with a lower-case S. (Single letters and letters in acronyms should always be capitalized.) Context makes it clear that someone writing about the “Oakland As” baseball team (are they still in Oakland?) isn’t saying something about “Oakland as” a city. Apostrophes are NEVER appropriate to use as an indicator of pluralization.

    I hope you will correct this single error on your otherwise extraordinarily excellent site. Thanks for your great resource, and for your attention.

    • Please note that we advise apostrophes only for single letters, not for acronyms or other groupings of two or more letters. Most authorities concur with our recommendations. Your theories on this matter are not supported by any stylebook we are aware of. It seems you have just decided to write your own rules.

      That being said, we certainly appreciate your kind words.

  3. Linda Latva says:

    We are going to amend the M-1’s (misdemeanor 1’s).

  4. Dan W says:

    A foreign student uses the apostrophe in a number such as 1st. He writes it as “1’st”. My English is not strong and I am trying to find the rule on this use. Can you please direct me on this subject?

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