Enumerate formulas

Question

I'm writing a math paper in LaTeX and for math formulas I'm just using $$math formula$$. Is is possible to numerate formulas? Or do I have to you use some specific commands such as align?

Answer 1

Vanilla displayed equation idioms:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

The \verb|equation| environment creates numbered formulas you can
label and refer to elsewhere:
%  this commented blank line prevents start of a new paragraph
\begin{equation}\label{eq:pythagoras}
a^2 + b^2 = c^2 .
\end{equation}
%  this commented blank line prevents start of a new paragraph
Equation~\ref{eq:pythagoras} is the heart of the Pythagorean theorem.

Use the \verb|\eqref| macro to put parentheses around equation
references: \eqref{eq:pythagoras}.

For equations with no numbers, use \verb|equation*|:
%
\begin{equation*}
2 + 2 = 4 .
\end{equation*}

For multiline formulas, use \verb|align| or \verb|align*|:
%
\begin{align}
e^{i\pi} & = \cos(\pi) + i\sin(\pi) \notag \\
       & = -1 .
\end{align}

\end{document}

Edit: TeX will complain if it sees a blank line before the \end of one of these environments. Debugging that error message is difficult since you tend to think that TeX automatically does the right thing with white space. See "File ended while scanning use of \align*"

Answer 2

For inline math use $...$ (or \( ... \)). For display math style equations, if you use aligned then alignment with enumerate's \item works better:

Code:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{enumerate}
\item $\begin{aligned}[t]
    E &= mc^2 \\
    F & = ma
\end{aligned}$
\item $\begin{aligned}[t]
    E &= mc^2 \\
    F & = ma
\end{aligned}$
\end{enumerate}
\end{document}