Latex Beamer Custom "Out of" Slide Number

I am doing Latex beamer and I want to have all slides appear out of 100 no matter how many slides I have.

So slide 1 will be: 1/100 slide 2 will be: 2/100 slide 3 will be: 3/100

I have no idea to do this?

Solution

With up-to-date beamer version:

\setbeamertemplate{page number in head/foot}{\insertframenumber /100}

(and maybe some footline template that shows the page number, but without seeing a minimal working example (MWE) that shows which theme your are using, this is pure speculation)

Compilable MWE:

\documentclass{beamer}

\usetheme{Berlin}
\setbeamertemplate{page number in head/foot}{\insertframenumber /100}

\begin{document}
\begin{frame}
content...
\end{frame}

\end{document}