This post originally appeared in a slightly different form on the BookMarks blog. Andrew Hacker is the author of The Math Myth and Other STEM Delusions, published this month by The New Press. Hacker, ...

Hear that change jingling in my pocket? Good. I have two little questions for you. I have a quarter, a dime and a nickel. How much money DO I have? I have three coins. How much money COULD I have? The ...