If the number of razor blades per razor keeps increasing, the individual blades will have to become thinner and thinner — giving a good example of the way math teachers teach the basics of calculus. In the meantime, the March 16, 2006 issue of The Economist offers this observation (and see their article for a nifty graph):
So what does the future hold? With only five data-points, it is hard to be sure exactly which mathematical curve is being followed. If it is what is known as a power law, then the 14-bladed razor should arrive in 2100. The spate of recent innovation, however, suggests it may be a hyperbola….
(Thanks to Steve Baum for bringing this to our attention.)