It depends on the quality of unique content of each site. If all the sites are crap, you will earn nothing.
Your earning depend on what type of keyword your website has. if your websites has high paying keyword like insurance you can earn lots of money from it.
You question is like how much i can earn from making 100 pizza. It depends on how many people click (buy) and how much the CPC (price you are selling)
well, your question is ...strange. you might get at least about $2 from each 1000 visits to your sites from adsense. doesn't matter how many sites you have, only the traffic and its quality makes money.
OP, nobody can answer that question. You could make 0 or thousands. It depends on you. How much work you put into them. If you did a lot of work and link building and got good traffic to them all and then had a decent ad setup that gets clicks you could almost retire. But not probable. Many try and I here "100" as a lot of peoples goals but most fail. Good luck in your earnings anyway. Probably all this is. IDKY I wasted my time writing this. lol
The question is really relative it could be nothing or million, but I make 600$per month with 100 pages. 10 of them are making the 70% profit of all sites.
It totally depends upon your traffic and unique content, so better try to implement it rather than asking people about earning etc, because i know some people who are earning $1000+ from even 2 sites.
I should tell you do not do like me do like DP they done the right thing and made one brilliant forum
Since there is no exact answer to your question, my advise or formula for you is this: start with one or 2 sites, put in as much work as you can in terms of quality and unique content, as well as building links (and i don't mean spamming people's websites.) Do this for about 6 months or more, and at that point pull out the ol' calculator and ask yourself; based on the revenue i've generated thus far, if i put in the exact same effort into 99 more sites simultaneously (which is almost impossible) then i would probably be making somewhere around: current revenue in $$ x 100. Good luck.
cannot answer blindly, niche, traffic and now facebook likes and twitter followers are also a factor for getting money from direct ads