Fifty Quarters

You have fifty quarters on the table in front of you. You are blindfolded and cannot discern whether a coin is heads up or tails up by feeling it. You are told that x coins are heads up, where 0 < x < 50. You are asked to separate the coins into two piles in such a way that the number of heads up coins in both piles is the same at the end. You may flip any coin over as many times as you want.

How can you do it?

Take x coins, flip all of them and put them in one pile. The rest of the coins form the second pile.

Posted in Brain Teasers

The Bookworm

A bookworm eats from the first page of an encyclopedia to the last page in a straight line. The encyclopedia consists of ten 1000-page volumes and is sitting on a bookshelf in the usual order. Not counting covers, title pages, etc., how many pages does the bookworm eat through?

        __                             __
      B|  |                           |  |F
      A|1 |...........................|10|R
      C|  |                           |  |O
      K|  |                           |  |N
       |__|                           |__|T
      -------------------------------------

On a book shelf the first page of the first volume is on the “inside”, so the bookworm eats only through the cover of the first volume, then 8 times 1000 pages of Volumes 2 – 9, then through the cover to the 1st page of Vol 10 for a total of 8,000 pages.

Note: The question asks how many pages, not how many sheets of paper.

Posted in Brain Teasers

Harvest Though No Grain

I harvest you, though you’ve no grain,
I reap you in the wind and rain,
You bleed not but your soft meat
And nectar makes a sweetest treat.
What am I?

A clam or oyster. You harvest clams or oysters on the beach or go diving, and the beach is often windy and rainy. Neither bleeds but are known for having, soft, slimy meat, and people often drink the “clam nectar” or “oyster juice”.

Thanks to Helena for this submission

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A Vowel-less Proverb

FLND HSMN YRSN PRTD

This is a well known proverb that has had all of its vowels removed. In addition, the letters have been broken up into groups of four while maintaining their correct order.

What is the proverb?

A fool and his money are soon parted.

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Everyone Is Doing This Same Thing

Right now everyone in the world, no matter where they are, is doing the exactly same thing. What is it?

Getting older. Sad but true, and there’s nothing anyone can do to stop it. If you thought of breathing, it’s not entirely accurate because not everyone takes a breath at the same time. Living is an arguably suitable alternate answer as well.

Posted in Riddles

A U2 Concert

U2 has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge. You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them.

The flashlight must be walked back and forth. It cannot be thrown and other tricks like that are not needed to solve the problem. The solution is simply a matter of allocating resources in a certain order. Each band member walks at a different speed. A pair must walk together at the rate of the slower man’s pace:

Bono: 1 minute to cross
Edge: 2 minutes to cross
Adam: 5 minutes to cross
Larry: 10 minutes to cross

For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.

This is one of my favorite brain teasers and I want to give you the satisfaction of figuring it out on your own. If you’re having a hard time, here’s a hint: There is a valid answer that doesn’t require tricks like throwing the flashlight or shining it backwards or having some other means of moving the flashlight.

There’s an assumption people often make that keeps them from solving this. Two members cross the bridge each time, but neither one of the two who crossed necessarily need to return. Think about how that would be possible. If you’re still stuck, use objects to simulate their movements. Use whatever you have laying around – pens, paper, erasers – and move them back and forth. Good luck!

Posted in Brain Teasers

Half of Eight

What is half of 8?

Hint: It’s not 4

3 (if you slice vertically) or 0 (if you slice horizontally)

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A King and Device of Measure

I am a king but also a common device of measure. What am I?

A ruler. A king is a ruler of people, a ruler is a device to measure distance.

Posted in Riddles

The Most Precious Commodity

What is the most precious commodity?
That which when needed seemingly is never enough,
Yet otherwise can be boringly plentiful.
While waking is oft dreamt of,
Whilst pining can scarcely be thought of.
For beings, is allotted in finite but indefinite quantity.
The more that’s given, the more is wasted.
Freedom is akin though this is something more simple,
Not related to virtue or sin.
Unless perhaps, without freedom, or its limit.

What is it?

Time.

(Thanks for submitting this one Duke)

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Buying Chickens

You must buy 100 chickens for exactly $100, and purchase at least one chicken from each store. The first store charges 5 cents/chicken, the second charges $1/chicken and the third charges $5/chicken. How many chickens should you buy from each store?

80 from store 1 = $4
1 from store 2 = $1
19 from store 3 = $95

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