# LaTeX symbol for “does not divide”

What is the correct way to make the "does not divide" symbol in plain LaTeX 2e?

I'm talking about the symbol that is a vertical bar with a slash through it. I prefer not to install AMS or other packages, but instead to use plain LaTeX.

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Have a look at “How to look up a math symbol?” for ideas how you can easily find a particular symbol. –  Caramdir Aug 9 '11 at 22:10
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## migrated from stackoverflow.comAug 9 '11 at 21:58

This question came from our site for professional and enthusiast programmers.

## 4 Answers

try this:

$x\nmid y$


it's been known to 'save the day'.

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That doesn't work in plain LaTeX. Do you know what package must be loaded to make it work? I tried \usepackage{amsfonts} but that doesn't work. And I still prefer a plain LaTeX solution. –  user448810 Aug 5 '11 at 22:33
I got \nmid working with \usepackage{amssymb}. –  user448810 Aug 5 '11 at 22:46
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Detexify is amazingly helpful in finding any symbol.

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Using \not with | works with plain LaTeX:

\documentclass{article}
\begin{document}
$2 \not| \;3$
\end{document}


The symbols \\, and \: and \; create varying degrees of space if the symbols get too close.

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I wonder why the \not introduces so much space. –  Dylan Moreland Jun 22 '12 at 1:11
I'm not sure which space you're talking about but try this: $2 \!\!\not| \,3$. The \! is negative space to get things closer together on the right and \, will reduce space on the right –  DJP Jun 22 '12 at 1:26
Oh, I didn't think you'd come back to this! Thanks very much. I just meant that while a|b is nice and compact, a\not|b puts a strange amount of space between a and |. –  Dylan Moreland Jun 22 '12 at 1:28
I don't know why \not has so much extra space but if I had to guess it might be because \not can be used in conjunction with a lot of other symbols which are wider than | [eg \not\in or \not\subset]. So some combinations will look better than others depending on the symbol width being negated. –  DJP Jun 22 '12 at 1:48
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To minimize used packages you can do this:
 \newcommand{\ndiv}{\hspace{-4pt}\not|\hspace{2pt}} 
From then on \ndiv will add the sign with appropriate spaces before and after.

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If the font size changes, this can cause a lot of headache. At least you can opt for units like ex,em but still it would not be robust enough to be used elsewhere. –  percusse Nov 27 '12 at 1:11
@percusse: can you provide a more robust way? –  cxxl May 23 at 8:02
@cxxl The answers above are pretty good. Otherwise you can look for the definitions from the LaTeX versions and carry them to plain TeX as raw macros. –  percusse May 23 at 20:55
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