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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]

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presidents
George Washington’s Incredible Hair Routine

America's Founding Fathers had some truly defining locks, but we tend to think of those well-coiffed white curls—with their black ribbon hair ties and perfectly-managed frizz—as being wigs. Not so in the case of the main man himself, George Washington.

As Robert Krulwich reported at National Geographic, a 2010 biography on our first president—Washington: A Life, by Ron Chernow—reveals that the man “never wore a wig.” In fact, his signature style was simply the result of an elaborately constructed coiffure that far surpasses most morning hair routines, and even some “fancy” hair routines.

The style Washington was sporting was actually a tough look for his day. In the late 18th century, such a hairdo would have been worn by military men.

While the hair itself was all real, the color was not. Washington’s true hue was a reddish brown color, which he powdered in a fashion that’s truly delightful to imagine. George would (likely) don a powdering robe, dip a puff made of silk strips into his powder of choice (there are a few options for what he might have used), bend his head over, and shake the puff out over his scalp in a big cloud.

To achieve the actual ‘do, Washington kept his hair long and would then pull it back into a tight braid or simply tie it at the back. This helped to showcase the forehead, which was very in vogue at the time. On occasion, he—or an attendant—would bunch the slack into a black silk bag at the nape of the neck, perhaps to help protect his clothing from the powder. Then he would fluff the hair on each side of his head to make “wings” and secure the look with pomade or good old natural oils.

To get a better sense of the play-by-play, check out the awesome illustrations by Wendy MacNaughton that accompany Krulwich’s post.

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"American Mall," Bloomberg
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Unwinnable Video Game Challenges You to Keep a Shopping Mall in Business
"American Mall," Bloomberg
"American Mall," Bloomberg

Shopping malls, once the cultural hub of every suburb in America, have become a punchline in the e-commerce era. There are plenty of malls around today, but they tend to be money pits, considering the hundreds of "dead malls" haunting the landscape. Just how hard is it to keep a mall afloat in the current economy? American Mall, a new video game from Bloomberg, attempts to give an answer.

After choosing which tycoon character you want as your stand-in, you're thrown into a mall—rendered in 1980s-style graphics—already struggling to stay in business. The building is filled with rats and garbage you have to clean up if you want to keep shoppers happy. Every few seconds you're contacted by another store owner begging you to lower their rent, and you must either take the loss or risk them packing up for good. When stores are vacated, it's your job to fill them, but it turns out there aren't too many businesses interested in setting up shop in a dying mall.

You can try gimmicks like food trucks and indoor playgrounds to keep customers interested, but in the end your mall will bleed too much money to support itself. You can try playing the bleak game for yourself here—maybe it will put some of the retail casualties of the last decade into perspective.

[h/t Co.Design]

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