"Making" to me tends to refer to profit, not gross revenue. In operating revenue, they made a few tens of millions last year on less than 1b gross. http://economictimes.indiatimes.com/infotech/internet/Facebo...

That's impressive, but they will have to double their profit several more times to warrant a 100b price tag.

Google has a PE ratio of 20. If you extend that to FB, they'll need to make 5b in revenue to get to 100b. Assuming that last year they banked 20mm, they would have to double their earnings eight times to get to 5b.