I'm teaching a course on quantitative reasoning for an audience of nearly two hundred math-averse students, and one of the ways I'm hoping to "sell the product" to them is to pitch the course as a kind of self-defense art that helps you not get ripped off by used car dealers, cell-phone companies, credit-card companies, banks, etc. For instance, I'll talk about the scam wherein the scammer sends free investment advice to 1024 people (half of whom get one piece of advice and half of whom get a conflicting piece of advice), then sends free advice to the 512 who got good advice on the first round (again splitting his advice half-and-half), then sends free advice to 256 people, and so on, and finally starts to ask a small number of people to pay a lot of money, hoping that they'll reason that someone who's been right so often must be onto something. I'll also show the class the grifting scene in "Paper Moon". Can any of you think of other good mathematical cons, or good resources for finding out about them? ("Ricky Jay's Big Book of Math Hustles" would be perfect if such a book existed!) Jim