Thanks to the Warren Buffett-backed Billion Dollar Bracket, more than ever before, outlets are reporting that the odds of picking a perfect bracket are "1 in 9.2 quintillion." This figure has been cited by The New York Times, USA Today, Slate, Bleacher Report, CBS, and Rick Reilly, among others, and it has to stop.
As most of these articles mention (after they've had their fun with this enormous number), 9.2 quintillion is 2^63, which means 1 in 9.2 quintillion are the odds of picking a correct bracket if you flip a coin for 64 games. Nobody actually picks brackets this way; even very casual fans incorporate relative seeding. For all practical purposes, 1 in 9.2 quintillion is a terrible estimate of how hard it is to pick a perfect bracket.
So what are real chances, if you're making even a somewhat informed decision? It's very difficult to calculate—Buffett himself has said that "Einstein himself could not figure out the odds"—but DePaul mathematician Jeffrey Bergen puts it at as low as 1 in 128 billion.
128 billion is still an enormous number—nobody's about to win Buffett's money—but it's not an astronomical one. If all seven billion people on Earth filled out a somewhat informed bracket with these odds, over the course of 13 years, chances would be greater than not (51 percent) that someone would nail it. If everyone filled out a coin-flip bracket, that break-even would come over the course of 911 million years.