Not Element Of in LaTeX (\notin)

Where it is used

States non-membership: the element on the left does not belong to the given set.

\notin is a dedicated slashed version of \in, typeset as a relation, as in \sqrt{2} \notin \mathbb{Q}. Writing \not\in gives a similar result, but \notin positions the slash better and is the standard choice. Its natural companions are \in and \ni, and for negated subsets you would use \not\subset or \nsubseteq. Typical sentences include proofs by contradiction and descriptions of complements, such as x \in A^c \iff x \notin A. In quantifiers, \forall x \notin S is acceptable shorthand but spelling out the domain is clearer.

Also listed under: Set Theory, Quantifiers

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage{amssymb}
\begin{document}
Not Element Of: $\notin$

\[ \sqrt{2} \notin \mathbb{Q}, \quad i \notin \mathbb{R} \]
\end{document}

Related symbols

• Subset\subset
• Element Of\in
• Union\cup
• Exists\exists
• Intersection\cap
• For All\forall

Frequently asked questions

How do I write Not Element Of in LaTeX?

Type \notin in math mode, for example $\sqrt{2} \notin \mathbb{Q}, \quad i \notin \mathbb{R}$. It works in plain LaTeX without loading any package.

Which package do I need for \notin?

None. \notin is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \notin in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\notin$ in running text. If you only need the glyph in text, paste the Unicode character ∉ instead (with XeLaTeX or LuaLaTeX and a font that has it).