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The Blue Book of Grammar and Punctuation

The Apostrophe with Letters, Numbers, and Abbreviations

Questions can often arise about how to make the plural and plural possessive forms of numbers, letters, and abbreviations. The following guidelines will help you apply a consistent style for everyday use.

Plural of Letters

Rule: The plurals for letters are typically not formed with apostrophes. However, do use an apostrophe and an s for the plural of a single letter if not doing so would make the meaning unclear.

Brian has three Bs on his report card.
Brian is the type of student who tries to dot all of his i’s (not is) and cross all of his t’s (not ts).
The children are studying their ABCs.
Please remember to capitalize your I’s
(not Is) when referring to yourself in your essay.

To form the plural of an abbreviation with capital letters, add an s with no apostrophe: M.D. > M.D.s.

To form the plural of an initialism, add an s with no apostrophe: one DVD but two DVDs.

Possessive of Letters (Apostrophe)

For an abbreviation that can be possessive in its context, add an apostrophe to the plural: She went to three M.D.s’ offices.

To form the possessive of an initialism, add an apostrophe to the plural: The DVDs’ new lower price could help them sell much faster.

If you wish to form the possessive of a single capital letter, add an apostrophe and an s after the letter: Plan A failed right away. Now it is Plan B’s fault that we can’t start the project. 

Plural of Numbers

To form the plural of a single-digit number, add an s: Her phone number has four 7s in it.

To form the plural of multi-digit numbers (such as for decades), add an s: the 1980s, the 1990s. The same principle applies to abbreviated numbers: Jake’s favorite movies are from the ’80s and ’90s. (Note that the apostrophe should be curving toward the missing numbers.)

If referring to two or more multi-digit numbers, maintain the same form for each figure: the 1980s and 1990s (not the 1980s and ’90s).

Possessive of Numbers (Apostrophe)

If you wish to form the possessive of a single number, add an apostrophe and an s: The number 7’s influence on my luck this month has been uncanny.

To create the possessive form of a multi-digit number, add an apostrophe to the plural: The 1970s’ influence on music that followed was unmistakable.

Pop Quiz

Now let’s review your understanding of the plural and the plural possessive with letters and numbers. Choose the correct form in each sentence.

  1. Darryl still dresses like he lives in the [1960’s / 1960s].
  2. Now I’ve learned my [ABCs / ABC’s], won’t you come and play with me?
  3. Be sure to mind your [ps and qs / p’s and q’s] at the formal dinner tonight.
  4. Bob’s poker hand includes a queen, a jack, and three [4’s / 4s].
  5. When the panel gives its presentation, Cherie says she’ll be most interested in the different [Ph.D.’s / Ph.D.s’] observations and opinions.


Pop Quiz Answers

  1. Darryl still dresses like he lives in the 1960s.
  2. Now I’ve learned my ABCs, won’t you come and play with me?
  3. Be sure to mind your p’s and q’s at the formal dinner tonight.
  4. Bob’s poker hand includes a queen, a jack, and three 4s.
  5. When the panel gives its presentation, Cherie says she’ll be most interested in the different Ph.D.s’ observations and opinions.

If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.

56 responses to “The Apostrophe with Letters, Numbers, 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?

    • 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.

      • Chan says:

        I don’t care if they are “authorities”! Who decided that these people were “authorities” anyway? Apostrophes are not used to form plurals – EVER!

        • We rely on the leading authorities recognized by writers in multiple fields including fiction, non-fiction, and newspaper and magazine reporting.
          According to the Associated Press Stylebook: SINGLE LETTERS: Use ‘s: Mind your p’s and q’s. He learned the three R’s and brought home a report card with four A’s and two B’s. The Oakland A’s won the pennant.

          The Chicago Manual of Style: 7.15: Plurals for letters, abbreviations, and numerals
          Capital letters used as words, numerals used as nouns, and abbreviations usually form the plural by adding s. To aid comprehension, lowercase letters form the plural with an apostrophe and an s (compare “two as in llama” with “two a’s in llama”).

          You may ignore authority or declare yourself an authority at your own risk.

          • Gigi F. says:

            I went through elementary school in the ’90s, and middle/high school in the ’00s, and I specifically remember learning to pluralize single letters by capitalizing them and avoiding using an apostrophe. An apostrophe is never appropriate for pluralizations, regardless of the word to be pluralized.

            That said, I understand language evolves, and I understand the apostrophe is common usage “for clarity.” I can’t say my own writing is ever perfect. I’m just writing here to confirm the other commenters’ message: that we were taught it is acceptable and “proper” to capitalize single letters and to avoid using apostrophes in plural forms. For example, I learned “Ps and Qs,” “ABCs,” and “Q & As” are proper grammar.

            Thanks for your informative website, and thanks for listening.

            • At the same time you were being taught your rules for pluralizing abbreviations and single letters, other students being taught by other teachers in other schools were being taught differently. Like you, we prefer no apostrophe when pluralizing abbreviations and single letters, as long as the meaning is clear. However, there is no universal agreement on the matter as we discuss in our Rules 2a and 6 of Apostrophes on our website.

  3. Linda Latva says:

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

    • We generally advise apostrophes only for single letters or numbers, but if adding the apostrophe avoids any potential confusion, many editors would add one.

  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?

  5. Joe Benincasa says:

    I haven’t seen this question in any forum before: in an article referring to college graduates from 2 different centuries (1900 through present), how does one distinguish the century in graduation year. For example, how do I know John Smith ’09 graduated in 1909 and not 2009? There are many graduation year notations, so reverting to something like “1909 graduate John Smith” would be cumbersome. Thanks for the assistance!

    • We have not seen specific guidance on this in any reference books. The only way to be sure of the century is to indicate the complete year. However, it could also depend on the context. If one is writing about graduates who are known to be alive, then ’09 should be sufficient since 1909 graduates would be over 125 years old.

  6. John Michael Shuffett says:

    What about when you have a possessive pronoun when the name is just the person’s initials? Should I drop the period preceding the apostrophe?
    For example, which is correct:
    A.J.’s coffee is black.
    A.J’s coffee is black.

    Thank you!

  7. paula says:

    Which is proper when stating:

    The healthcare system received all As in their safety programs. OR The healthcare system received all A’s in their safety programs.

    • As the post states, “For clarity, most writers use apostrophes with single capital letters and single-digit numbers.” Also note a correction to your sentence:
      The healthcare system received all A’s in its safety programs.

  8. rick says:

    Is the usage correct?

    Mig21’s had made missile attacks on two other B52’s in the area on previous nights.

    The three B52’s separated so they could land.

  9. Amy Genova says:

    How do you show possession for an ordinal possessive such as Elizabeth I’s reign?

    • Since we would say, “Queen Elizabeth the First’s reign,” it would be written “Queen Elizabeth I’s reign.” You could avoid this somewhat awkward construction simply by recasting as “The reign of Queen Elizabeth I.”

  10. Mohamad sulaiman says:

    How do you use apostrophe before numbers? example: ” I think this style is from the ’70 not from the ’80.

  11. Vicki says:

    I teach three year olds. How do I write a heading for a class list….Three’s Class List or Threes Class List? Similarly, when describing my job, do I write “I have been teaching the 3’s class since 2017,” or “I have been teaching the 3s class since 2017”? When describing the class, is it “In the 3s class, we are reading…” or 3’s?
    Thank you for any clarification you can give.

    • The Chicago Manual of Style and The Associated Press Stylebook recommend writing out the number three. (Please see our Rules for Writing Numbers.) You could consider the word Threes as an adjective describing the words class list and class, therefore eliminating the necessity of an apostophe (Threes Class List, threes class). Since you are referring to a group of children who are three years old, your other option would be to use the plural possessive (Threes’ Class List, threes’ class). See our post Apostrophes and False Possessives for more information.

  12. Nichole says:

    Life Community Church is sending an email to announce a meeting.
    “Please join us for a meeting where we will discuss LCCs vision for expanding…..”

    LCC’s or LCCs? I like the “cleaner” look of LCCs, but will defer to you!

    • This post addresses only the fairly rare use of apostrophes with plurals of numbers, letters, and abbreviations. For your case of a possessive with an abbreviation, you should write “LCC’s vision.”

  13. Rajni Saini says:

    If we are using an abbreviation for a term and giving its expanded form before the abbreviation (in parentheses), where should the apostrophe go? With the expanded term or with the abbreviation (after the closing parenthesis)? For example, The State Bank of India’s (SBI) credit profile is underpinned by several factors or The State Bank of India (SBI)’s credit profile is underpinned by several factors?

    • The State Bank of India’s (SBI’s) credit profile is underpinned by several factors.
      Or, you can work around this situation by writing:
      The credit profile of the State Bank of India (SBI) is underpinned by several factors.

  14. Michelle says:

    I am a teacher and I have always thought that Year 6s should be written without the apostrophe as it is a plural of a group of Year 6 students.

    A lot of other teachers write it is Year 6’s though. Are we both correct?

    • Our apostrophe rules have been updated since the time this article was posted on our blog. Apostrophe Rule 6 now includes this sentence: “Single-digit numbers are usually spelled out, but when they aren’t, you are just as likely to see 2s and 3s as 2’s and 3’s.” Depending on the context, we would likely agree with you on omitting the apostrophe to distinguish the plural from the possessive, but it’s a matter of style and preference. It would be nice if your school could establish one style for all teachers to use.

  15. Brian Cerow says:

    In alphabetizing proper names, where is a name like d’Agustino listed, under the “A’s,” “D’s,” or somewhere else?

  16. Jerboa says:

    What is the possessive form of ‘90s ?
    Is it ‘90s’ as in (if spelled out) nineties’ fashion or (if in numbers) ‘90s’ fashion? This would mean the fashion of the nineties or the fashion of the ‘90s. Correct?
    Or should it just say ‘90s fashion?

    • This can be a matter of distinction between an adjective that needs no apostrophe or a possessive noun, which we explain in greater detail in Apostrophes and False Possessives. In this case, we would interpret ’90s (or 1990s or nineties) as an adjective to describe the noun fashion. In this case, an apostrophe is not necessary.
      However, a different construction might force a style call, such as “The ’90s’ (or 1990s’ or nineties’) main legacy was…” In this case, to avoid awkward punctuation, we could recast as “The main legacy of the ’90s was …”

  17. Layla says:

    My teacher was saying how I should use commas instead of apostrophes for numbers that go over three digit. (ex. 193,302. instead of 193’302) Which one is correct or does it not really matter?

    • It does matter, and your teacher is correct. Our Rule 3a of Writing Numbers says, “With figures of four or more digits, use commas. Count three spaces to the left to place the first comma. Continue placing commas after every three digits. Important: do not include decimal points when doing the counting.” Therefore, 193,302 is correct.

  18. Nova says:

    How about the place value such as Ones,tens,hundreds,Thousands, etc..
    How would you discussed their places..
    Is it ones? Or one’s?
    Like Ones place or One’s place?

  19. Jayant Kochar says:

    If a group of people use the term 95ers to describe themselves as having graduated in 1995, which of these is most appropriate?
    ‘95ers (indicating that 1995 has been contracted to 95)?
    95’ers (indicating that they “belong” to 1995)?
    ’95’ers (I believe it is better to avoid 2 apostrophes in one word?

  20. Karyn Scherer says:

    Could you please give your opinion on how you write the possessive of the acronym/initialism WasteMINZ? Should it be WasteMINZ’ or WasteMINZ’s?

  21. Caroline says:

    Many of my colleagues use apostrophes for plurals of abbreviations, such as SME’s and KPI’s and T&C’s. When I correct them, their argument is that the apostrophe is being used, because the word is being abbreviated, i.e. because the C in T&Cs stands for “conditions” and the apostrophe indicates that there are missing letters. What is your take on this? I know it’s technically incorrect, but is language evolving this way? Thank you.

  22. Pat Phelps says:

    I spent my adult life as a Language Arts teacher and I taught these pluralizations as you have described so well. This method of pluralization was demeaned by someone claiming to be a teacher, saying that it “is a big mistake in British or Commonwealth English, although I gather it’s very common in the American dialect.” Is that so? Do the British have different rules about this?

    • says:

      American English typically discourages using an apostrophe to form a plural unless it is necessary to help avoid confusion, as in Please remember to dot your i’s (as opposed to …dot your is.). While do we explore some of the differences between U.S. and U.K. English (see our articles beginning with “American vs. British English”), we are not familiar with British guidance or style in this area. Perhaps one of our readers across the pond will see this thread and inform us.

  23. Patty says:

    If a company’s acronym ends in a S, then how do you use apostrophes?

    For example,
    a.) CAS’ expert team will assess the damage …or…
    b.) CAS’s expert team will assess the damage.

    Thank you.

    • says:

      Since a company name is a singular proper noun, we recommend using ‘s. However, some style guides recommend just an apostrophe after proper nouns, including company names, when they end in the letter s.

  24. olaf k fjetland says:

    If I am referring to a particular period of time, 1980, and want to indicate that there was a crisis happening, which would be correct: 1980’s Crisis or 1980s’ Crisis?

  25. Vikki says:

    Please advise why in educational settings a lower case “s” is used when abbreviating the word “school.” The PTA is known as FOLs, “Friends of Lychgate School.” Why is the “s” not also capitalized?

    • says:

      We do not recognize why “Friends of Lynchgate School” would not be a fully capitalized initialism (FOLS).

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