[startupper]

So FB makes:

15.8x10^9(pageviews/month)x0.01x0.04/100 + 0.25x15.8x10^6 = $4x10^6 per month on ads?

So their annual revenue is just under $50x10^6 or $50 million.

Note: this assumes one ad per page.

[run4yourlives]

$50 Million isn't nearly enough for 15.8 billion pageviews.

There's a lot of overhead cutting down the profits there. (Probably why there's an IPO rumour.)