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# The Number of the Day: 16,000

Mountains beneath Antarctica's ice sheets rise 16,000 feet.

Related Link: Vacation to Mars: Photos of Antarctica's Dry Valleys, by Ransom Riggs

[Source: National Geographic Answer Book: Fast Facts About Our World (available for preorder). 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.

What Number Is The Answer?

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