300,000 has been the go-to number for us reporters when someone asks how many iPads have sold. Quite frankly, we just don't know. Apple hasn't been talking, and probably won't until sales hit some milestone (like, say, a million), leaving us to rely on market analysts for an idea. Well, an advertising firm called Chitika claims to know exactly how many iPads are out there, or, at least how many iPads are using the Internet.
Chitika's system works by tallying up the number of iPads that use the company's advertising network, and then the firm "[multiplies] that by how much of the Internet we see at any given time to figure out how many iPads in total are out there." That means that 600,000* could even be too low, but it's what Chitika considers to be the number of known iPads.
According to the company there are:
Over 607,000 iPads in the wild as of this writing (and counting)
Over 99,000 new iPads discovered today alone
Double the number of iPads in California, accounting for 19% of sales
You can see a live tally as well as a state-by-state breakdown of Chitika's statistics by hitting up the company's website at the link below.
*Update: It looks like Chitika's methods need a little refining, as the company turned out to be overgenerous. Apple announced that the company has sold 450,000 iPads to date.