Four Chains in One Loop

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

Three cuts. Cut each link in one chain. Separate them, and use the links to join the ends of the three intact chains.

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Alter By a Single Stroke

How can you alter the following equation by a single stroke to make it correct?

5 + 5 + 5 = 550

5 4 5 + 5 = 550

Add a diagonal line on the top left of the first plus sign to convert + into a 4. You could also put a slash through the equal sign to make ≠ (not equal) but that’s not as cool.

Posted in Brain Teasers

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

Two Identical Women

Two women apply for a job. They are identical and have the same mother, father and birthday. The interviewer asks, “Are you twins?” to which they honestly reply, “No”.

How is this possible?

They are triplets.

Posted in Brain Teasers

The Right Combination of Letters and Values

The letters A through H can be assigned the following values to make all the equations true. Find the right combination of letter values.

Values: 1, 4, 5, 7, 9, 14, 16, 21

C + F = G
A + C = F
B + G = D
B + E = H
D + F = H

A = 1
B = 7
C = 4
D = 16
E = 14
F = 5
G = 9
H = 21

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I Have Hundreds of Legs

I have hundreds of legs but I can only lean,
You make me feel dirty so you can feel clean.

What am I?

A broom.

Posted in Riddles
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Apples Rebus

What does this represent?

APPLE
APPLE
APPLE
aPPLe
APPLE

I haven’t figured this out yet. Bad apple doesn’t really fit with the lowercase letters. They’re both vowels, but I don’t know if that’s relevant. The fourth one looks kind of like a hill, could it be apple hill?

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Shortest Word With All the Vowels

What is the shortest word in the English language to contain all of the vowels?

Sequoia, eulogia or miaoued are all good options, but there’s an even shorter (and more obscure) word with all the vowels and not a single consonant: Iouea. It’s not the kind of word you’d use at the dinner table, but it’s listed in the Wikipedia dictionary as a genus of Cretaceous fossil sponges.

If you got really tricky and tried to find a word that contained the letters in the phrase ‘all of the vowels’, you probably found, like I did, that there isn’t one. But it was still worth checking.

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Black We Are And Much Admired

Black we are and much admired,
men seek us if they are tired,
We tire the horse, comfort man,
guess this riddle if you can.

Coal.

Posted in Riddles

How Many Mangoes?

From a basket of mangoes when counted in twos there was one extra,
counted in threes there were two extra,
counted in fours there were three extra,
counted in fives there were four extra,
counted in sixes there were five extra,
but counted in sevens there were no extras.

At least how many mangoes were there in the basket?

119. The number has to be evenly divisible by seven for there to be no extras when counting in sevens, and it has to be odd in order for there to be one extra when counting by twos. It also can’t be evenly divisible by three through six. 119 is the first odd multiple of 7 that satisfies the requirements.

Posted in Brain Teasers