# See If You Can Solve This Tricky Coin-Flipping Riddle

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Make sure your head is in working order before trying to solve this riddle from TED-Ed, because it's a stumper.

Here's the scenario: You're an explorer who's just stumbled upon a trove of valuable coins in a remote dungeon. Each coin has a gold side and a silver side, each with an identical scorpion seal. The wizard who guards the coins agrees to let you have them, but he won't let you leave the room unless you separate the hoard into two piles with an equal number of coins with the silver side facing up in each. You've just counted the total number of silver-side-up coins—20—when the lights go out. In the dark, you have no way of knowing which half of a coin is silver and which half is gold. How do you divide the pile without looking at it?

As TED-Ed explains, the task is fairly easy to complete, no psychic powers required. All you need to do is remove any 20 coins from the pile at random and flip them over. No matter what combination of coins you choose, you will suddenly have a number of silver-side-up coins that's equal to whatever is left in the pile. If every coin you pulled was originally gold-side-up, flipping them would give you 20 more silver-side-up coins. If you chose 13 gold-side-up coins and seven of the silver-side coins, you'd be left with 13 silver coins in the first pile and 13 silver ones in your new stack after flipping it over.

The solution is simple, but the algebra behind it may take a little more effort to comprehend. For the full explanation and a bonus riddle, check out the video from TED-Ed below.

[h/t TED-Ed]

# New Harry Potter Scrabble Accepts Wizarding Words Like Hogwarts and Dobby

USAopoly

Patronus, Hogwarts, and Dobby may not be words found in the official Scrabble dictionary, but they are very real to Harry Potter fans. Now there's finally a board game that lets players win points using the magical vocabulary made famous by the Harry Potter books and movies. SCRABBLE: World of Harry Potter from USAopoly is a new edition of Scrabble that recognizes characters, place names, spells, and potions from J.K. Rowling's Wizarding World.

Like traditional Scrabble, players use the letter tiles they pick up to spell out words on the board, with different words earning different point values. Any word you can find in an up-to-date Merriam-Webster Dictionary is still fair game, but in this version, terms coined in Harry Potter qualify as well. First and last names, whether they belong to characters (Albus or Dumbledore, for example) or actors from the franchise (Emma or Watson), are playable. You can also spell magical place names (like Hogsmeade), spells (accio), and objects (snitch).

USAopoly

Showing off the depth of your Harry Potter knowledge isn't the only reason to put wizarding words on the board. Magical words are worth bonus points, with players earning more points the longer the word is. SCRABBLE: World of Harry Potter also includes cards with special challenges for players—a feature that can't be found in any other version of the game.

This Harry Potter edition of Scrabble will be available for \$30 at Barnes & Noble and other retailers this spring. Until then, there are plenty of Harry Potter-themed games, including wizarding chess, out there for you to play.

USAopoly

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