I'm wrtiting my Master of Science thesis in Aerospace Engineering and I've a doubt about wrtiting of ordinal numbers? Let' us consider the following alternatives:$i$th, $i$-th. What is the correct form, with or without hyphen?

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    related (on a sister SE): tex.stackexchange.com/q/10959/2061
    – Ran G.
    Commented Nov 25, 2022 at 12:39
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    All such style issues will be different place-to-place. Get guidance from the place you hope to publish. For your thesis, that would be your university or department of your school. Hopefully you are using LaTeX and you can just change style files to update it if you have the wrong one. latex-project.org/get
    – Boba Fit
    Commented Nov 25, 2022 at 17:52
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    I clicked on this question thinking that you meant "ordinal number" in the sense of "en.wikipedia.org/wiki/Ordinal_number." The mathematics tag may be overkill here. Commented Nov 29, 2022 at 23:25

1 Answer 1


The specific case of "nth" is often written even outside technical contexts, and without a hyphen, see e.g. Merriam-Webster's definition. So I would prefer $n$th, etc.

I don't recall ever seeing a version with a hyphen used, but I have occasionally seen "th" as a superscript. A common error here is to have the "th" in math mode; the right way to use a superscript is $n$\textsuperscript{th}.

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