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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

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

2 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.

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