Professor Strang explains how the "magic number e" connects to ordinary things like the interest on a bank account. The graph of y = e^x has the special property that its slope equals its height (it goes up "exponentially fast"!). This is the great function of calculus. View the complete course at: http://ocw.mit.edu/OcwWeb/resources/RES-18-005Spring-2010/ResourceHome/index.htm License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu