According to http://www.nua.ie/surveys/how_many_online/index.html we’re looking at a worldwide total of 544.2 million people hooked up worldwide - I think this includes people with internet access either at home or at work.
Again, according to their figures this breaks down to:
4.15 million in Africa
157.49 million in Asia/Pacific
171.35 million in Europe
4.65 million in Middle East
181.23 million in Canada & USA
25.33 million in Latin America
Warning, many wild assumptions and quite possibly very bad math below:
Taking the world figure of 544.2 million people, and plucking out the air an average megahertz speed of 400mhz (again, assuming that everything hooked up is Intel PC based, which of course it isn’t), and figuring that a 400mhz PC can perform 100 million calculations per second (again assuming 5 cycles per calculation) then we’re looking at a total calculations per second figure for all hooked up people of:
Or, 54 quadrillion, 420 trillion calculations per second.