If any cry of anguish is universal across generations, it's this one, said by kids in Algebra classes throughout the land: "Why do I have to do this stuff? Am I ever going to use it in real life?" Kids and adults alike acknowledge that we use elementary-school math in real life on a daily basis. We add, subtract, multiply and divide quite frequently. But when teachers start replacing the numbers with letters, and are introduced to terms such as "variable" and "polynomial", then those instructors meet resistance from students, and their protests often center around the idea that this kind of math will do them no good in the real world. A lazy adult will simply affirm the students' suspicions by admitting that complex algebraic problems don't make their way into everyday life. It's an easy thing to say, but the truth is that life is full of situations in which formulas are required or at least helpful. Here are some math formulas tha...