That's it. How can I know how many i386 and amd64 packages exit available in repos?
From a bit of poking in
[jk@pecola ~]$ for f in /var/lib/apt/lists/*binary-*_Packages; do echo -n $(basename "$f")": "; grep '^Package:' "$f" | wc -l ; done apt:9999_ubuntu_dists_precise_main_binary-amd64_Packages: 8204 apt:9999_ubuntu_dists_precise_main_binary-i386_Packages: 8221 apt:9999_ubuntu_dists_precise_multiverse_binary-amd64_Packages: 688 apt:9999_ubuntu_dists_precise_multiverse_binary-i386_Packages: 700 apt:9999_ubuntu_dists_precise_restricted_binary-amd64_Packages: 21 apt:9999_ubuntu_dists_precise_restricted_binary-i386_Packages: 21 apt:9999_ubuntu_dists_precise_universe_binary-amd64_Packages: 29593 apt:9999_ubuntu_dists_precise_universe_binary-i386_Packages: 29647
This is assuming you're interested in built packages, rather than sources (one source may be used to build a number of installable .debs). Also, this number is specific to the repos that I have set up on my machine (main, restricted, universe and multiverse).