Maybe you thought your days of grinding through word problems ended when you sold that college algebra textbook back to the university bookstore (for less than half of its original price). But if you’re a rehab therapist who treats Medicare patients, you probably have to call upon your math skills—and maybe even the ol’ TI-83 Plus—fairly often, because sometimes Medicare’s 8-minute rule seems more like a complex trigonometric function than a seemingly straightforward billing formula.

Think you’ve got the 8-minute rule on lock? Take this quiz to test your smarts. (Need a quick study session first? Check out this blog post.)