By default, equation numbers are place on the right side of an equation for any numbered math environment, such as `equation`

, `eqnarray`

, and `align`

. Surprisingly, the equation number position can is changed through the optional `documentclass`

argument `leqno`

:

**Left numbering**

\documentclass[leqno]{article}

**Right numbering** (by default and therefore usually skipped):

\documentclass[reqno]{article}

Here is a minimal working example:

\documentclass[a4paper,12pt, leqno]{article}
\usepackage{amsmath}
\begin{document}
\subsubsection*{Equation:}
\begin{equation}
f(x)=ax^2+bx+c
\end{equation}
\subsubsection*{Align:}
\begin{align}
f_1(x)&=a_1x^2+b_1x+c_1\\
f_2(x)&=a_2x^2+b_2x+c_2
\end{align}
\end{document}

Align is part of the amsmath package which was used here because there are several reasons to avoid eqnarray.

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copiancestral

Nice post. I actually found quite useful the avoid eqnarray tip. It’s just one of those things that one struggles with, but you really don’t think there’s an easy way around it. Thanks!

tom

Hmmm, maybe I should summarize the key points of avoid eqnarray in one of my future posts…

Thanks for your comment! Tom.

Humberto

Yes, it is a great post. I want to change the Chapter numbering to Roman numbers, but keeping Algebraic numbering for Figures, Tables and equations not Roman numbering. How I can do it?

Thanks for any advice,

Humberto

tom

Please see my reply to the same question on another post.

Cheers, Tom.

B. I. Dave

Very helpful command of LHS numbering.

Thanks a lot !