Suppose I want to say that the (base 10) representation of a million contains 6 zeros, but for whatever reason, I want to use the symbol 0 rather than the word. Is there any rule on how to attach the "s" to make 0 plural? I have seen "0-s", "0's" and "0s" in various papers, but, sadly, it is not the case that these are always written in perfect English).

Of course, this issue is not unique to zeros. I might want to talk about how many times the number 42 appears in a book by Douglas Adams, or how many times the variable x appears in an equation. In general - how does one attach the suffix "s" to make a plural of something which is not a word?

Note: I am not sure if there is any rule about this, but nonexistence of such rule would also be useful to know about. Likewise, if making non-words plural is bad English, then that would be good to know too.

marked as duplicate by Lawrence, Dan Bron, user66974, Edwin Ashworth, Laurel Apr 3 '17 at 19:13

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ODO's website says this on the matter


There are one or two cases in which it is acceptable to use an apostrophe to form a plural, purely for the sake of clarity:

  • you can use an apostrophe to show the plurals of single letters:

I've dotted the i's and crossed the t's.

Find all the p's in appear.

  • you can use an apostrophe to show the plurals of single numbers:

Find all the number 7’s.

These are the only cases in which it is generally considered acceptable to use an apostrophe to form plurals: remember that an apostrophe should never be used to form the plural of ordinary nouns, names, abbreviations, or numerical dates.

  • 2
    ODO is not OED. Have you evidence that OED also endorses these views? – Edwin Ashworth Apr 3 '17 at 19:01

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