ok -- I have gotten a few answers to this question but

ok -- I have gotten a few answers to this question but I still do not know what I have to do --

OK -- I am using domain mapping -- each domain(50 of them) has 2 sub domains and the three of them x 50 are mapped to theactionsociety.com

actioninaustin.com mapped to ----> austinbusiness.theactionsociety.com classifieds.actioninaustin.com mapped to ---> austinclassifieds.theactionsociety.com & realestate.actioninaustin.com mapped to ---> austinrealestate.theactionsociety.com

Now how many facebook applications do I need ---

under app domains in the app creation when you click on the "?" says: Enable auth on domain and subdomains example theactionsociety.com will enable *.theactionsociety.com

but when I setup one of these FB installs using the action society app ----

In step 3 of instructions in the WP dashboard -- it says
"Look for Site URL field in the Web Site tab and enter your site URL in this field: http://floridakeysclassifieds.theactionsociety.com"

the site url already has http://theactionsociety.com.

Now I have been told I need a different app for each site, it has also been suggested that I can do it with just one app --

Lets say -- you say I need an app for each domain -- then I ask do I need a seperate app for each sub-domain of the mapped domain --- for instance -- do I need 3 apps one for each actioninaustin.com classifieds.actioninaustin.com realestate.actioninaustin.com

1 app for all
1 app for every group of three
1 app for each individual