You can really understand it by breaking down the possibilities like Dr. James Grime does in the video below. We'll break them down here for you, too.

- Say you choose Door #1, and the car is in Door #1. Monty Hall opens Door #3 to reveal a goat. In this case, if you switch, you
**lose**. - Say you choose Door #1 and the car is in Door #2. Monty Hall opens Door #3 to reveal a goat. In this case, if you switch, you
**win**. - Say you choose Door #1 and the car is in Door #3. But Monty Hall wouldn't open Door #3 to reveal a car, because that ends the game prematurely. Instead, he'd open Door #2 to reveal a goat. Again, in this case, if you switch, you
**win**.

As you can see, switching wins you the car two out of three times, because Monty is essentially giving you a choice to either open Door #1 only, or to open both Door #2 and Door #3. It seems incredibly counterintuitive, but that's probability for you.

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*For mathematical puzzles from the reigning king of mathematical puzzles, check out "The Colossal Book of Short Puzzles and Problems" by Martin Gardner. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.*