Ignoring page numbers in backup slides

Question

I am using the beamer document class in latex to make a presentation. I will have a number of back up slides which are there for offline viewing, reference etc. Beamer has a f

Answer 1

The great command \insertpresentationendpage will take care of your problem. Just place \appendix at the begin of your backup slides.

\documentclass[t]{beamer}

\usepackage[absolute,overlay]{textpos}
\setbeamertemplate{navigation symbols}{}

\def\insertpresentationendframe{\inserttotalframenumber}
\makeatletter
\g@addto@macro{\appendix}{\immediate\write\@auxout{\string\@writefile{nav}{\noexpand\headcommand{\noexpand\def\noexpand\insertpresentationendframe{\the\c@framenumber}}}}}
\makeatother

\setbeamertemplate{footline}{%
    \begin{picture}(54,12.5)(0,0)
    \put(0.9,0.52){%
        \begin{minipage}[b][12.5mm][c]{112.5mm}
        \raggedleft
        \insertframenumber/\insertpresentationendframe
        \end{minipage}
    }
    \end{picture}
}

\begin{document}

    \begin{frame}
        slide in the main part
        \only<2>{blub}
    \end{frame}

    \appendix
    \section*{Backup}

    \begin{frame}
        \frametitle{backup}
        not counting in the total frame number
    \end{frame}

\end{document}