So I was in Times Square with some fellow computer nerds, and someone got to wondering how much power all those signs used. Then someone asked, if it were powered entirely by people running on treadmills, how many people would be needed? After a lot of math and some debate about human physiology, we concluded that something on the order of 1,000,000 people (I can’t remember the exact figure) would need to be running on treadmills 24/7 to power all the ads.