# [Tex/LaTex] How to you number equations manually

equationsnumbering

How to number equations manually? I'm making a presentation on a chapter, so would like my equations to be numbered as in the book, and not necessarily from the first equation in the chapter, for example, if the first equation in my document is numbered (5.23).
Thank you.

You should load the amsmath package (if you don't do so already) and use its \tag macro to assign whatever number or symbol you like to a given equation. Cross-references to such equations can be made via the usual \label--\ref (or \eqref) mechanism.

\documentclass{article}
\usepackage{amsmath}      % for \tag and \eqref macros
\setlength\textwidth{7cm} % just for this example
\begin{document}
$1+1=2 \tag{5.23} \label{eq:special}$
A cross-reference to equation \eqref{eq:special}.
\end{document}


Compile the example code twice so that LaTeX can resolve the cross-reference.