# How to number an entire array environment with only a single number [duplicate]

Possible Duplicate:
numbering few equations together

I am currently using an align environment to write a system of equations. The code has the form:

\begin{align*}\label{myEnv}
%equation 1 here
%equation 2 here
%equation 3 here
\end{align*}


I am wondering how I can number this environment using only a single number. Right now if I change align* back to align, I will get three different numbers for each line within the environment.

I know for a fact that \label{myEnv} returns the correct number, but I don't know how to display it within the actual LaTeX document.

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Perhaps try align with \nonumber for the lines you do not want to be numbered? – André Mar 29 '12 at 1:12

## marked as duplicate by Peter Grill, Gonzalo Medina, Alan Munn, Thorsten, Joseph Wright♦Mar 29 '12 at 6:03

This can be done with the split environment inside the align environment:

\documentclass{minimal}
\usepackage{amsmath}
\begin{document}
\begin{align}\label{myEnv}
\begin{split}
equation 1 here \\
equation 2 here \\
equation 3 here
\end{split}
\end{align}
\ref{myEnv} contains one number
\end{document}

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you can use:

\documentclass{minimal}
\usepackage{amsmath}
\begin{document}

For alignment use this:
\begin{align}\label{myEnv}
\begin{split}
a &= b + c + d \\
a &= b + c  \\
av &= b + c
\end{split}
\end{align}
\ref{myEnv} contains one number

For centered use this:
\begin{align}\label{myEnv1}
\begin{gathered}
a = b + c + d \\
a = b + c  \\
av = b + c
\end{gathered}
\end{align}
\ref{myEnv1} contains one number
\end{document}

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