1) Let's find a relatively rare name (otherwise we have to do much more clicking). For example, "Molly Fisher".<p>2) Search it on Google+: 4 results, but one of them has not accepted invitation yet, so it's 3 actually.<p>3) Let's make the same search on Facebook. They do not show user count, but let you click "See More Results". Click it why there are more results (21 times). That gives approximetely 215 results.<p>4) See Facebook claimed user base on Wikipedia - 750 millions.<p>5) 750 / 215 * 3 ~= 10 millions.<p>P.S. Other search suggests about 7.5 millions on Google+
I read somewhere that you could extrapolate all the information about the universe from a tea cake. Somewhere...<p>Anyhoo - don't panic. I have my towel on the ready.