Want to find a percentage of one number relative to another? With a calculator, it's easy. And this free video math lesson will show you how to go about it. 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).