Answer:
There are about 500 million active users, and the average user makes about 4 page requests per day. When I load the facebook homepage for my account it loads about 150 resources, because of their use of ajax there are anywhere from 1 to 100 more resources used per page request.
So after all the math there are about 2 billion page requests, which equates to about 100 billion resource requests (images, scripts, style rules, etc.)