Need to find the mean (that is, the regular average) of a set of numbers? It's easy! So easy, in fact, that this clip can present an overview in just under 45 seconds' time. Learn how with this free video lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).