http://www.google.com/search?hl=en&safe=off&q=site:forums.digitalpoint.com&btnG=Search thats how many pages google has indexed from DP forums. just replace the URL with another site.
you can find out how many pages were indexed by google (search for site:abcdefg.xyz) ... this gives you a good approximation on how many pages are in the website. or you could by lucky and get a hold on the sitemap. try pointing your browser to www. abcdefgh .xyz/sitemap.xml