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votes
1answer
144 views

Curved lines on a paper [closed]

There are curved lines drawn on a piece of paper. Lines can have two characteristics: One of its endpoints is on another characteristic 1 line One of its endpoints is on another characteristic 2 line,...
2
votes
1answer
424 views

Whose lock is lock-ier?

Two friends, Amy and Ben, each use a three-disk combination lock to secure their bikes. Each disk has $10$ orientations, with integers $0$ to $9$, so there are $10^3$ possible combinations. One day, ...
4
votes
1answer
275 views

Don't worry, I won't byte

... I am pretty hungry though. Figure out what I want to eat: 01001001 00011111 01000100 10110100 11110101 10010001 00011111 01000001 10111101 10110011 01100000 01100110 10000110 11000010 10001000 ...
9
votes
2answers
1k views

Second star to the right and straight on 'til morning

Remember to look up at the stars and not down at your feet. Try to make sense of what you see... We look up at the same stars and see such different things. So I looked up, second to the right he ...
7
votes
1answer
372 views

Eureka!: A Riddle

The first one borne, the others belated. Legions have my intentions debated. Headdress upholding my endless mission; I rule either way, death or submission. Gather your might to face my ...
13
votes
2answers
1k views

The Erasmus polyhedron

Professor Erasmus has constructed a special convex polyhedron from perfectly homogeneous material, which he modestly calls the "Professor-Erasmus-polyhedron". The professor claims that he can put the ...
14
votes
9answers
4k views

What are my friends' names? (A visual puzzle)

While messing around at one evening, I made six small drawings, one for each friend of mine. My drawings were made to be very specific: Taking the action or object represented in any of them, you can ...
4
votes
3answers
1k views

An outer-space riddle

Twinkle twinkle little star How I wonder what you are In the sky just passing by You can vanish in the blink of an eye Moving at speeds I can't believe All the things you can achieve In an atmosphere ...
6
votes
5answers
1k views

A rare sight indeed

Source of an element that never existed Perhaps with thermal tangles Some of us are not as neat Our name is a misnomer An electronic errand? Hard to pinpoint Following death We fade too Question: ...
-3
votes
1answer
410 views

Math sequence puzzle

Complete the sequence: 5928 1411 9909 1882 5419 ... It doesn't seem like a simple polynomial fit will work, I have tried the difference method and the quotient method. Any hint would be appreciated. ...
8
votes
1answer
548 views

Message to Survivors

Your spaceship pulls out of uberdrive (a new transportation mode that has overtaken hyperdrive in the space exploration market) and you find yourself gazing at the beauty of Earth for the first time ...
4
votes
9answers
2k views

The London safes and their mysterious combinations

Here's the first riddle I invented for Puzzling SE. Hope you'll enjoy solving it. This story takes place during World War II. A German spy is assigned the task to sneak overnight into a military base ...
2
votes
1answer
180 views

Round plates on a round table [duplicate]

(I did not make this one up, but it's one of my favorites and I didn't see it on here!) After a long shift at the restaurant, your fellow waiter Jeremiah proposes the following game: Start with an ...
2
votes
2answers
254 views

N strings in a bag

There are n strings in a bag. In one pass, you randomly pick one end of a string and then one more string. Then you tie these two ends together and put the resulting string back into the bag. Then ...
8
votes
2answers
778 views

The mini-facebook puzzle

The database of mini-facebook only has space for the data of 100 participants. These 100 participants want to establish as many mini-facebook friendships among them as possible. However, mini-facebook ...
1
vote
3answers
529 views

Knowledge about common knowledge (hats puzzle)

$n$ villagers wear either black or white hats. The truth is that all the hats are black, but this is not known. They sit in a line, so that each villager can see all the hats in front of them, but not ...
0
votes
2answers
1k views

Make a glass sit above two other glasses using only a regular banknote [closed]

On a table there are three cups and one banknote (a dollar bill will do). These are the only objects you may use, with the goal of placing one of the cups, upright, above the other two, without any ...
-2
votes
2answers
1k views

What is the minimum number of line segments that need to be made to cross all points on a $n \times m$ grid?

Given a grid of $n \times m$ points, on a sheet of paper, what's the minimum amount of lines (which can extend infinitely) required to pass through each point, that you can draw without lifting a ...
1
vote
1answer
170 views

Flag carrying ants in a ring [duplicate]

There are $n$ ants randomly distributed on a ring facing clockwise or anticlockwise. Each ant is carrying a flag numbered $1,\ldots,n$. They all start moving around the ring at the same speed (in the ...
5
votes
1answer
216 views

Word Matrices, Level 2

This puzzle is based on NeedAName's recent puzzle, Determinant of Word Matrix. The challenge: Create a $3\times3$ matrix of distinct letters (i.e. no repeated letters) with no vowels in the ...
-6
votes
1answer
214 views

Bob and Steve find an ambiguous sentence - but HOW ambiguous? [closed]

Bob is mentoring Steve at a new job, and they are working their way through some poorly written instructions to install an update for some critical software. Things are going okay up until they find ...
4
votes
3answers
582 views

What is the largest, compact connected-network polyomino for these tiles?

This is a graphical arrangement puzzle. Consider the following 36 tiles: Each tile has up to 8 connected directions and each tile has an initial up side. (The edge to whose centre the central ...
0
votes
1answer
479 views

seven thief and equal coins [duplicate]

Seven thieves are to distribute a number of coins between themselves. They find that it splits equally, but being astute mathematicians, they realize that if there were 2, 3, 4, 5, or 6 thieves to ...
4
votes
5answers
471 views

Determinant of Word Matrix

Challenge: Create a 3x3 matrix of letters (NO REPEATS) such that the determinant of the matrix forms words from the 'multiplications'. For example, in a simple 2x2 case, take the matrix $\begin{...
13
votes
3answers
672 views

Exponential time in a Blue Eyes variant

I created a variant of the Blue Eyes problem where the logic took 4901 days (over 13 years) to totally play out. I thought this was nice, but I was hoping for an even longer period of time. Of ...
5
votes
4answers
2k views

Complete the sequence

As the title says it is a compete the sequence. My thoughts: From all the circle ones that aren't a circle, you can make a circle by rotating the pieces. From all the triangle ones that aren't a ...
7
votes
2answers
959 views

What date can it be?

To save money, a meticulous person had a oddly unique way of splurging money. Each day the person would splurge an amount equal to the month-digits + day dollars. So for the first of April it would ...
2
votes
2answers
658 views

Which of the options fit the sequence?

Which of these tiles would fit the sequence? I've tried to think about it but I have no idea.
5
votes
3answers
598 views

Mr. Hilbert and the Problem of the Nuanced Napkin Ring [closed]

Mr. Hilbert was sitting alone at the dinner table of the Grand Hotel restaurant, waiting for his two friends, Mr. Euler and Mr. Langrange, to show up. It was 5 minutes past six already, but knowing ...
22
votes
5answers
4k views

Worm and an Apple

Johnny has a perfectly spherical apple, with a diameter of 70 mm. While he looks away, a worm burrows through (entering and leaving) the apple, forming a single tunnel of length 69 mm and negligible ...
8
votes
5answers
20k views

Meeting of hands on a clock

We have a regular analog clock with three hands - second, minute and hour. On a given day, how many times do: (a) the minute and hour hands (b) the minute and second hands (c) the hour and second ...
8
votes
1answer
498 views

Redesignated students

Class 6F at Farthingbottom School was very unusual this year. All the students had transferred from a School in the USA. Today was their first history lesson with Professor Flavanna. "Welcome, ...
10
votes
3answers
601 views

Find the fastest path through this Brazilian concretist poem

One day, a small jet was flying over the concretist poem "Velocidade" (Speed), by the Brazilian poet Ronaldo Azeredo. In order to cover every vowel present in this poem, it goes in straight line from ...
15
votes
4answers
4k views

For how long did Lisa walk?

Lisa gets picked up from work by her husband at exactly 4 pm every day. One day Lisa finished work half an hour earlier and started walking to meet up with her husband. She met her husband on the way, ...
3
votes
2answers
439 views

Professor Halfbrain's quadrilateral theorem

Professor Halfbrain has recently made a fascinating discovery on quadrilaterals in the plane. Halfbrain's quadrilateral theorem: Let $ABCD$ be a plane quadrilateral that possesses an incircle and ...
15
votes
5answers
1k views

Evaporating coins

In the country of Dalgonia, there is only one type of fake coins and only one type of genuine coins. All genuine coins have the same weight. All fake coins have the same weight. Fake coins and ...
4
votes
1answer
725 views

Empty Rectangles - Does the rule apply when the intersection takes place inside the box with the empty rectangle?

The Empty Rectangles method is a strategy for solving Sudoku puzzles. I have seen the description of this strategy here, I have the following question: Is there a problem if the other end of the ...
19
votes
1answer
730 views

Numbered Logicians near the Blue Eyes island

There is an island near the famous Blue Eyes island where 100 perfect logicians live, each with a number between 1 and 100 (repetitions allowed) tattooed on their forehead. They know all the numbers ...
1
vote
7answers
355 views

The Buzzer Game [closed]

Two players, A and B, are each given air horns. Also present is a device which will at some random point produce a noise. If the device produces a noise before either player, they die. If both players ...
8
votes
4answers
872 views

How to leave me behind

If you wish to leave, then there's no doubt first you must look for the way out. Then with open eyes you must stare; just look down to meet my glare. To remember this ordeal, to take my ...
3
votes
1answer
591 views

Movies in movies

Each clue references a movie. Take all of the clues, combine them, and solve that clue to get you one final movie. Where did the literally animated little guy and his family come from? What type was ...
8
votes
3answers
475 views

Professor Delvershys calculations

After spending half of the night with important calculations Professor Delvershy arrived late this morning. To his dismay he discovered that one of his students used the unexpected spare time to ...
8
votes
2answers
781 views

Termite eating through a large cube composed of 27 smaller cubes while not moving diagonally

The is a large cube formed by gluing together 27 smaller cubes of uniform size (see figure). A termite starts at the center of a face of any of the outside cubes and bores a path that takes him once ...
25
votes
1answer
1k views

Careless smokers

Cosmo complains: "At the party yesterday at our place, some guys were smoking in our living room. This morning we detected that these careless smokers had burnt four holes into the carpet." Fredo: "...
12
votes
1answer
438 views

Morse of the films that I've watched a lot

After my last attempt to compile a movie list, we replaced Paul's keyboard and tried again. Once again I dictated a list of my favourite movies to Paul and he typed them up. He then gave the list to ...
8
votes
3answers
1k views

Four Letter Word

What's a four letter word that sounds exactly the same if you take away the first and last letters?
-3
votes
1answer
372 views

Find the number and the trend?

I was raised this question in my PSA exam and I am still not able to find the answer.The question reads:: Find the number to replace the "???" in the given box and the trend used to find it either row-...
15
votes
1answer
1k views

In which cities do the following puns apply?

Each of the following phrases refers to a specific city on Earth. You'll find out what I mean when you get the answers. In which city... ...is there a giant blockade to prevent small rodents from ...
24
votes
3answers
1k views

I've seen these movies countless ties

I wanted to make a puzzle for you all with some help from my friends so I dictated a list of my favourite movies to Paul and he typed them up. He then gave the list to Alice to describe the titles.I ...
14
votes
8answers
721 views

Cryptic Jeopardy

Puzzlers! Welcome to Cryptic Jeopardy, where your cryptic-crossword solving skills will be pushed to their limits -- in direct competition with your fellow puzzlers! Here's how it works: If you see a ...

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