Beamer frame numbering in appendix

I've used the following macros for this purpose:

\newcommand{\backupbegin}{
   \newcounter{framenumberappendix}
   \setcounter{framenumberappendix}{\value{framenumber}}
}
\newcommand{\backupend}{
   \addtocounter{framenumberappendix}{-\value{framenumber}}
   \addtocounter{framenumber}{\value{framenumberappendix}} 
}

The bonus slides are then put between the two commands:

\appendix
\backupbegin

\frame{\frametitle{One more thing}}

\backupend

This will get you the desired numbering, too.

I had the same problem and found the answer on stackoverflow.

The answer is very simple, just include the appendixnumberbeamer package:

\usepackage{appendixnumberbeamer}

You can enable the (undocumented) noframenumbering option for each frame in the appendix. This also works for omitting the title page in the frame total.

\begin{document}
\begin{frame}[plain,noframenumbering]
  \titlepage
\end{frame}
...
\appendix
\begin{frame}[noframenumbering]
  ...
\end{frame}
\end{document}

Unfortunately this setting isn't inherited by additional frames resulting from allowframebreaks. To fix this, add the following to your preamble.

\usepackage{etoolbox}
\makeatletter
\preto{\appendix}{%
  \patchcmd{\beamer@continueautobreak}{\refstepcounter{framenumber}}{}{}{}}
\makeatother