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Win a Copy of the National Geographic Answer Book!

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Every day, more than 20,000 Chinese people leave the countryside to settle in urban areas.


Related Link: For the past two weeks, we've been pulling Numbers of the Day from the beautiful and fascinating National Geographic Answer Book, which hit stores last Tuesday. You can order your copy from the National Geographic Store.


Want to Win a Copy? Leave a comment with an amazing demographic fact. We'll pick our favorite on Monday and award that person the book!


[See previous Numbers of the Day here.]

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This Puzzling Math Brain Teaser Has a Simple Solution
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Fans of number-based brainteasers might find themselves pleasantly stumped by the following question, posed by TED-Ed’s Alex Gendler: Which sequence of integers comes next?

1, 11, 21, 1211, 111221, ?

Mathematicians may recognize this pattern as a specific type of number sequence—called a “look-and-say sequence"—that yields a distinct pattern. As for those who aren't number enthusiasts, they should try reading the numbers they see aloud (so that 1 becomes "one one," 11 is "two ones," 21 is "one two, one one,” and so on) to figure the answer.

Still can’t crack the code? Learn the surprisingly simple secret to solving the sequence by watching the video below.

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What Number Is The Answer?
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