Use following command:
manpath
it will show you path of man pages
example:
user@Null-Pointer:$ manpath
/usr/local/man:/usr/local/share/man:/usr/share/man
If you take a look in the directory you will see all tar files..so almost all the man pages are stored in tar archive format and they are extracted on the fly when you ask for some man pages using
man some-command-