I offer to pay you $200 in one year if you give me $190 today. Good deal or bad deal? It’s the kind of math problem you might encounter in real life, as opposed to, say, whether the cosecant of a ...

Add Yahoo as a preferred source to see more of our stories on Google. We like to think that we're pretty good at math, especially after years of schooling. But every once in a while, a simple ...