FatalMath Mode
Missing Dollar Sign (Math Outside Math Mode)
! Missing $ inserted.
What this error means
A math command or symbol (like _, ^, \alpha, \frac) was used outside of math mode. LaTeX only interprets these as math when they appear between $ delimiters or inside a math environment.
Common causes
- Using _ for subscript or ^ for superscript in normal text
- Using \alpha, \beta, or other Greek letters outside math mode
- Forgetting to open math mode with $ or \(
- An \end{equation} closed the environment but math symbols follow
How to fix it
Wrap math content in inline math mode with $...$ or \(...\), or use a display math environment like \begin{equation}...\end{equation}. For subscripts in text use \textsubscript{} and for superscripts use \textsuperscript{}.
Code examples
Causes the error
\documentclass{article}
\begin{document}
The value is x_1 + y^2 = z.
Let \alpha be a constant.
\end{document}Fixed
\documentclass{article}
\begin{document}
The value is $x_1 + y^2 = z$.
Let $\alpha$ be a constant.
\end{document}Related errors
Test the fix live
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