star numbers – Math for Grownups https://mathforgrownups.com Books to improve your math Wed, 16 Sep 2020 11:03:14 +0000 en-US hourly 1 https://wordpress.org/?v=5.4.5 7 Reasons 21 is Special (Hint: The Rapture Ain’t One of Them!) https://mathforgrownups.com/7-reasons-21-is-special-hint-the-rapture-aint-one-of-them/ Fri, 20 May 2011 02:55:03 +0000 https://mathforgrownups.com/?p=25 So tomorrow the world is supposed to end. Okay, not quite. The rapture will begin.  Apparently Earth won’t be destroyed until October 21. So you have some time to get your $@*% together. But this isn’t the only reason that the number 21 is significant. Here are some other interesting (in a pocket-protector kind of way) [...]

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]]> So tomorrow the world is supposed to end. Okay, not quite. The rapture will begin.  Apparently Earth won’t be destroyed until October 21. So you have some time to get your $@*% together.

But this isn’t the only reason that the number 21 is significant. Here are some other interesting (in a pocket-protector kind of way) facts about this Very Important Number.

  1. 21 is the sum of the dots on a die: 1 + 2 + 3 + 4 + 5 + 6 = 21
  2. 21 is a Fibonacci number: 1, 1, 2, 3, 5, 8, 13, 21, …
  3. 21 is the third “star number.”
  4. 21 is smallest number of differently sized squares that are needed to tile a square.
  5. 21 is the legal drinking age in the U.S. (Not so math geeky, eh?)
  6. Blackjack baby!
  7. {221}-21 is a prime number.

Anything you want to add?  Or are you too busy packing your bags?

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