test

Equations can get reference numbers using the \tag{} macro, e.g:

\[E=mc^2\tag{1}\] produces \[E=mc^2\tag{1}\]

Note that the contents of \tag{} are in text mode, so if you want to include math symbols, use \tag{$...$}. E.g.,

\[E=mc^2\tag{$\bullet$}\] produces \[E=mc^2\tag{$\bullet$}\] \begin{equation} (x-aw)^2 +(y-bw)^2 =r^2w^2. \tag{2} \end{equation}