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The 'Monty Hall Problem': Your Guide To The Controversial Math Fact That Drives People Insane

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Monty Hall Slidedeck
Walter Hickey/BI

Several days ago, we published a slide deck of 12 math problems designed to stir up controversy. 

The response was enormous — millions of clicks, more than a hundred comments, and a barrage of angry emails.

One problem, however, caused by far the most dissent: The Monty Hall Problem, a problem inspired by the famous game show Let's Make A Deal.

Here, we'll go into even more detail to prove one of the most contested ideas in all of math. 

If you didn't get it on the first go around, don't worry. Even Paul Erdős, one of the most respected and prolific mathematicians in history, didn't believe the result until he saw a computer simulation. 

This one goes out to all the Monty Hall "Truthers" out there. You know who you are.  

Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI

images via Wikimedia

Monty Hall Slidedeck
Walter Hickey/BI

images via Wikimedia

Monty Hall Slidedeck
Walter Hickey/BI

images via Wikimedia

Monty Hall Slidedeck
Walter Hickey/BI

images via Wikimedia

Monty Hall Slidedeck
Walter Hickey/BI

images via Wikimedia

Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI
Controversial Math slideshow
Walter Hickey/BI
Monty Hall Slidedeck
Walter Hickey/BI

Is your mind sufficiently blown? If not, click ahead...

Controversial Math slideshow
Walter Hickey/BI

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Walt was Business Insider's Deputy Editor for Data and Analysis.Hickey is the author of You Are What You Watch, and also writes Numlock News, a daily morning newsletter. He came from FiveThirtyEight where he was chief culture writer. Walt previously worked at Business Insider from 2012 to 2013, and  graduated from The College of William and Mary with a degree in Applied Mathematics. In additon to his work on elections and data journalism, he also edits comics at Business Insider.In 2022, Hickey won the Pulitzer Prize for Illustrated Reporting for his work on Business Insider's I Escaped A Chinese Internment Camp documenting the plight of Uyghurs in China.