# How to get the closing single quote in math mode

How to get the closing single quote in math mode. The apostrophe in math mode is displayed as prime.

\documentclass{article}
\begin{document}
Why can't I get $a'$ in math mode.
\end{document}

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You should switch to text-mode, eg.

\documentclass{article}
\begin{document}
Why can't I get $a\textrm'$ in math mode
\end{document}

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that's it. thanks! –  Oxdeadbeef Mar 20 '12 at 21:37

Punctuation that is not part of a formula should go outside the formula:

When $$a>0$$, we say that $$a$$ is \emph{positive}.

In the interval $$[0,1]$$ there are infinitely many rational numbers.


It's quite rare that quotes are used as math symbols, but I've seen them in some textbook on mathematical logic. Since ' is used for denoting a prime (dash) in math, one can resort to a different trick: the lines

\DeclareMathSymbol{\mlq}{\mathord}{operators}{}
\DeclareMathSymbol{\mrq}{\mathord}{operators}{'}


will define two commands that will give left and right quotes in math and your input can become

Why can't I get $\mlq a\mrq$ in math mode.


but in this case $a$' should be probably better.

I've added a companion to \mrq just for symmetry and, perhaps, greater clarity.

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