The article uses a simple sports betting example and gets it wrong: > At the start of the season you’ve made a bet that the Green Bay Packers will get to the S

The article uses a simple sports betting example and gets it wrong: > At the start of the season you’ve made a bet that the Green Bay Packers will get to the Super Bowl, at odds of twenty to one. You put down ten bucks. The team advances to the conference championship, where it’s playing the San Francisco 49ers. At this point, you decide to hedge your bet by putting ten dollars on the 49ers, who are three-to-one favorites to win the game. You’re guaranteed a profit, whatever the outcome. So you made two bets: * $10 at 20:1 for Packers, pays $10 + $10 * 20/1 = $210 * $10 at 1:3 for 49ers, pays $10 + $10 * 1/3 = $13.33 You spent a total of $20. Assuming the house takes no fee, you might win $190 or lose $6.67. If you didn't spot the error, perhaps the author tricked you in a way quite analogous to what the article complains about: by skimming over the actual math and using a lot of words, the banker (or author) might make you believe "You're guaranteed a profit, whatever the outcome." If you want to guarantee a profit, put e.g. $150 on the 49ers. Then you'll have a net profit of $50 ($210 - $10 - $150) if the Packers win, and $40 ($200 - $10 - $150) if the 49ers win. That's a better hedge; the perfect hedge is left as an exercise.