I used the package beamer outer theme split numbered
to make it for themes with navigation. But the theme Hannover
is different. Is re-defining the footline the only choice, or is there some other convenient way?
Update: the solutions like
\useoutertheme{infolines}
or
\setbeamertemplate{footline}{\insertframenumber/\inserttotalframenumber}
can both do the job, but not so grace as I expect. Both of them will ruin the layout of Hannover. It is better to put the page number on the bottom of the left column, or at the left side of the navigation row.
Best Answer
If you only want to have the slide numbers in the footer, I use this (I adapted Matthews code):
For more details on how to modify beamer templates you can also have a look at the Beamer User Guide