# All Questions

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### The Blown Lightbulbs [duplicate]

Sitting on the table are 3 light bulbs. 1 of them just blown, 1 of them has been blown for ages, and the other works fine. You don't which is which, but you're allowed to test (turn on) 1 bulb . How ...
1k views

### A sequence named by a children's toy [duplicate]

Here's a part of the sequence: (A) (B) (C) (D) (E) 1113122113 311311222113 ... The letters are the missing members (there are 5 missing members) and A is the ...
8k views

### What is the shortest known rubik's cube algorithm?

This is related to this question, but different. I'm not asking for the least number of moves needed, nor for pointers on how to use fewer moves. In Singmeister's notes (an 80's book!) there is ...
418 views

### Shortest time interval measurable via burning a rope

You are given some matches, a rope, and a pair of scissors. The rope burns irregularly and takes 60 minutes to burn end to end; however, we know that the burn rate at distance $x$ from the left end is ...
199 views

### Where to manufacture a 3D wood puzzle?

I have a design for a puzzle I want to develop. It requires fairly good accuracy when cutting the pieces which have complicated shapes, although they all are made of equal size cubes. Eventually I ...
775 views

### The Secret Passcode

A top secret facility is guarded by 1 man, this man will kill anyone with the wrong, or without a, passcode. There are 5 spies. They have determined the code is one of the following; Orange Apple ...
660 views

### The Long Bus Ride [closed]

I expect multiple answers to this, however only 1 of them is correct. A bus was scheduled to stop 10 times today. Each time, 7 people got on the bus and 5 got off. At the last stop, how many people ...
9k views

### Hungry lions and a goat

There are 53 lions in a cage and 1 goat. All the lions are very hungry and would want to eat the goat. But the problem here is that any lion who eats the goat can satisfy his hunger but he will ...
1k views

### How do I find more enigmatic, no-clues-given puzzles?

Most of my awareness of puzzles and puzzle games has come from a decade of haphazardly stumbling around the internet. There's a flavor/genre that I particularly enjoy, but I haven't had much luck ...
1k views

### The Tricky Tunnels!

The king had a mutant rat problem in his kingdom, so he ordered 3 young men to go down under the depth of the ground to find the cause. The 3 young men jumped down the hole, and followed the tunnel. ...
611 views

### A Second Benjamin Button

This was inspired by A curious case of Benjamin Button but has a different solution. In 1980 AD (or 1980 CE, if you prefer), Jack has an age of 20. In 1985 however, he is only 6 years old. How did ...
1k views

### Hidden Message: Of Shapes and Numbers

I've created a puzzle quite a while back, unfortunately not many people wanted to play so I'm posting here instead. The idea is that the image can be decipher to uncover a hidden message. The hint is ...
517 views

### A curious case of Benjamin Button

In 1980, Jack has an age of 20. In 1985 however, he is only 15 years old. How did he age backwards?
1k views

### A boy and his father [closed]

A young boy is taking a ride with his dad when a truck runs them off the road, killing the father and critically injuring the young boy. He's Medivac'd to the nearest hospital as the child is lying on ...
2k views

### Elevator puzzle [closed]

A guy lives in the 10th floor of an apartment building. On a normal day he goes to the 5th floor with the elevator and then climbs the remaining 5 floors. On a rainy day he goes to the 10th floor ...
1k views

### 2048 - Maximum score that doesn't rely on luck

Inspired by this thread: Largest possible tile in 2048, I've always wondered with such games to what extent you NEED luck to be able to get to a high score. For example, the maximum tile of 131072 ...
12k views

### How do I solve this put-together spherical puzzle?

In a set of puzzles I found online recently, I acquired this unnamed puzzle: I'm not sure what it is, or how to solve it. It definitely comes apart, as it is split into six pieces, but I see no ...
3k views

### The Laziest Surveyor

The new land surveyor and his boss arrived at the work site, a huge and perfectly flat parking lot. His boss said, "Your first assignment is going to be a tough one. You see this parking lot? It ...
470 views

### What does this encoded message mean? “kzsaain zhps V !vW”

The following message was encoded using a simple algorithm: !kzsaain zhps V !vW Please try to explain how it works.
1k views

### How to ship the new Slurm 7-pack efficiently

The six-pack is a thing of the past. Beverages of the future will use the seven-pack format. But how will the mighty spacemen of the future manage to ship the Slurm seven-pack efficiently in ...
2k views

### What is the number 4.9292683…?

Guess the next digits of this number. Where does it came from? 4.9292683
688 views

### Infinite Troll Tolls

So, recently there was a very good riddle posted here: Paying the Troll toll. I would like to propose a similar question which might have been partially answered. But anyways... So, same basic idea ...
3k views

### Cora's Death Logic Puzzle

When Cora was killed, Anna and Beth were questioned by the police about the manner of her death by poison. Anna: If it was a murder, Beth did it. Beth: If it was not suicide, it was murder. The ...
1k views

### What are the next 5 numbers in the sequence?

It's a simple pattern I thought of. Here it is: 1,1,1,3,3,6,6,10,10,22,22,44,44,84,?,?,?,?,? Whoever gives the correct answer and a good explanation gets best answer.
876 views

### About Knights and Knaves and their consistency

On an Island of Knights and Knaves (where Knights always tell the truth and Knaves always lie), a Knight will never contradict himself unless some true fact changes. I was wondering: can a Knave ...
974 views

### Witches and Cats

This being Halloween, we will consider the problem of witches and their cats. The whole crowd is out tonight, naturally, and an interested observer, seeing them fly by (yes, witches' cats fly), ...
631 views

### Recover the Ripped Quote

Bruce found a nice quote on the web, then wrote it in on a square piece of paper and left it somewhere in his room. The quote had exactly 64 characters excluding spaces. He has written the characters ...
537 views

### Odd birthdate surprise

Last year, just before my birthday in February, I noticed something unsual. The last two digits of my birth year were the same as my age. How old was I then and was this an unusual occurrence?
1k views

### The Ball Factory Worker

A woman works at a ball factory. She's instructed to open up a ball creation kit composed of one red rubber ball and two strips of digit stickers from $0$ through $9$. She's instructed to do the ...
30k views

### Find 10 triangles in a five pointed star using two straight lines

This puzzle consists of counting ten triangles (check three sides for each one, remember that there aren't exist triangles with more than three sides :P ) using two straight lines that cross the ...
9k views

The unexpected hanging paradox is as follows: A judge tells a condemned prisoner that he will be hanged at noon on one weekday in the following week but that the execution will be a surprise to ...
2k views

### About the island of Knights and Knaves

On one of the Islands of Knights and Knaves you land for the purposes of an anthropological survey. The Island has Knights who always tell the truth ( if they know enough information regarding a ...
385 views

### Oxford versus Cambridge - a geographical puzzle [closed]

What is a geographical similarity between Cambridge University and Oxford University related to their 'titles'?
557 views

### How to let all people in Group A talk to all people in Group B in a shortest amount of time?

Ok, let say Group A has N number of people, and Group B has M number of people. I want each person in Group A to have a fixed T time conversation ( time T is fixed like 5 min or 10 min) with each ...
601 views

### origin of the “missing dollar puzzle”

I am wondering when the missing dollar puzzle first appeared. I am sure I read it forty years ago or so, but maybe it is much older. Does anyone knows it?
264 views

### Non-Diagonal Pointing Problem

You can see the rules for pointing problem at this article. It has been clarified that there is no solution to this question. But, what if we remove the diagonal rule? is there any solution?
6k views

### Write digits 1 to 9 in the table, each pointing to next 3x3 grid

Write 1 to 9 digits in an empty Sudoku table with these rules (similar to 9-Queen problem): There are 9 Boxes indexed from 1 to 9 in the image below. and each box has a 3x3 grid child. Every two ...
1k views

### Horses and Tracks

I have seen this question before and I am intrigued that there might be various ways it can be solved. I do know of one way, but I am trying to find out if there is any other approach possible. The ...
2k views

### Where has the last dollar gone?

Lately I have found different versions of this puzzle, I was wondering if it has a name or belongs to a specific kind, so that I can understand it better. Here it is: Peter got \\$10 from his father,...
2k views

### Two Card Probability Problem

I came across this puzzle somewhere on the interwebs. Has stumped me for an answer for quite sometime. Helpplease? Someone picks, at their will, two cards from a deck of cards. The cards have ...
2k views

### Find the next symbol in this sequence

I just came up with the following puzzle. I don't think anything like this has been asked here before, but I may be wrong. What's the next symbol in this sequence?
19k views

### Difficult IQ test question: What is the box suggesting?

I found a Very Difficult IQ Test on web. One of its questions is: What is the box suggesting? I have seen the answer but there was no clues for the logic behind that. 123456789 176h54308 627456934 ...
824 views

Grelling's Paradox is about certain types of words. An adjective is heterological if it does not describe itself; like 'long', 'German', or 'monosyllabic'. An adjective is autological if it does ...
9k views

### Interview Question or Pathbreaking puzzle

I thought this changes the way series of numbers are looked at 1 1 1 2 1 1 2 1 1 Write down the next three lines
2k views

### A square and a circle at once [closed]

Can you draw something on a piece of paper that looks like a square and a circle at the same time? ( without using Math or 3-d visualisation techniques)
685 views

### What drives the brain when creating puzzles?

From as far back as psychologists Robert Sternberg, and Janet Davidson argued that solving puzzles entails the ability to compare hidden information in a puzzle with information already in memory, and,...
2k views

### Of men and hats

There's an obvious generalization of this problem: There are a rather large number of prisoners, each of them seeing the color of the hat of all the following sad fellows bot not their; the hats may ...
8k views

### Chaos and Order: a visual puzzle in stained glass

I created a visual puzzle, which my wife then implemented as part of a stained-glass window. I've no idea if it is (a) obvious, (b) stupid or hopefully (c) extremely clever, and hence would love to ...