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Mike Benzie | NCAA.com | March 12, 2017

March Madness bracket: The difficulty in picking a perfect Sweet 16 in the NCAA tournamentodds behind Warren Buffett’s 2017 March Madness bracket contest

  The 2015 NCAA Tournament yielded a somewhat stable and popular Sweet 16, and because of that, a higher percentage of bracket participants got the Sweet 16 perfect. In most years, nobody gets 16 for 16 in this round.
  The 2015 NCAA Tournament yielded a somewhat stable and popular Sweet 16, and because of that, a higher percentage of bracket participants got the Sweet 16 perfect. In most years, nobody gets 16 for 16 in this round.

The odds of picking a perfect bracket are pretty much impossible. But picking a perfect Sweet 16 -- and only a perfect Sweet 16 -- is more do-able, even if the odds are still in lottery territory. 

MARCH MADNESS SHOP
We looked at millions of brackets over the past six years in the Capital One March Madness Bracket Challenge Game to get an idea of the likelihood.

The odds of nailing the Sweet 16 (picking all 16 second-round games correctly) -- without figuring any favorites, just going by pure chance -- are around 1 in 4 billion, according to Tim Chartier, a Davidson computer science professor who runs a March Mathness website and uses a data tool devised by Charlotte-based Tresata for his bracket crunching.

The odds are probably a little better than that if you take into consideration some basic facts of the tournament. A 16 seed has never made the Sweet 16, for example, and a 15 seed has advanced just once in more than 30 years. So removing some double-digit seeds from the equation changes the odds significantly, though it's still a ridiculously long shot.

More: Longest a bracket has stayed perfect  |  Lessons from past bracket winners

We also have data and experience to draw on in trying to improve those odds. In 2015, only one double-digit seed made the Sweet 16: UCLA. All 16 teams – aside from maybe 7 seed Wichita State – would have been considered popular picks.

That year, ESPN reported 14 perfect Sweet 16s among the 11.57 million brackets played in its game. Fourteen perfectos sounds like a lot, but even then, that’s just one perfect 16 in every 826,000 tries. 

And remember, 2015 was an outlier. Across the years, Sweet 16 perfection is far harder to come by. In the last six years of the Capital One March Madness Bracket Challenge, an average of 1 in 1.85 million have picked perfect Sweet 16s, with several years having no one going perfect.

Last year, the No. 10 Syracuse-No. 11 Gonzaga line probably busted a ton of chances at a flawless Sweet 16. Throw in a (6) Notre Dame vs. (7) Wisconsin and picking a perfect Sweet 16 proved literally impossible. No one picked every team in the Sweet 16 last year in the Capital One March Madness Bracket Challenge

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Siddesh Malkarnekar contributed to this report.

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