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1500 questions
50
votes
7 answers
How many tries to roll a 6?
Suppose you roll a (fair, 6-sided, perfectly ordinary) die repeatedly until you roll a 6. As is well known, the expected (i.e., long-term average over many trials) number of rolls required is 6.
Now suppose we ask this question conditional on never…
Gareth McCaughan
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50
votes
7 answers
Are you clever enough?
I'm always in your thoughts, technically twice
If displayed correctly, just to be precise
If you see my left you will call me a con
and it would tear me apart if you called me John
Take down a note and drop your cup
All you need is what keeps…
Avigrail
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50
votes
15 answers
Find the identity of the four troll brothers
The four troll brothers Wudhor, Xhaqan, Yijlob and Zrowag have the following properties:
Wudhor always says the truth.
Xhaqan always lies.
Yijlob lies or says the truth unpredictably.
Zrowag is deaf and never answers.
You are brought in front of…
Lynn
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- 6
- 12
50
votes
3 answers
Locate the hacker
This is my first time making one of these. Hopefully it's not too easy (or too difficult). Let me know what you think. If people enjoy this I will make more!
It is May 26th, 2016
After years on the run, government authorities were able to find the…
cbronson
- 655
- 5
- 14
50
votes
12 answers
Challenge for lovers
One of my friends gave me this puzzle. Please help me find the answer for it.
Jane and Mike have fallen in love, and Mike wishes to send her a ring via mail. Unfortunately they live in Kleptopia where anything sent by mail will be stolen unless it…
Supriya S
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- 6
50
votes
1 answer
Edward's Maze I
Edward's "revenge" on Bob the mute house servant
Edward had enough! This was it! During the yearly sorcerer meet in a
hidden cellar in Léon, Edward discovered a red stain on his precious robe.
First he thought that it was just blood - but no,…
Katai
- 1,163
- 7
- 12
49
votes
3 answers
Cover 63 squares of a chess board
Can you find 3 similar geometrical figures (common shape but can be different sizes) A, B and C with the following property:
If you remove any square from a 8x8 chess board, then the remaining area can be exactly covered with A, B and C.
How do A, B…
ThomasL
- 12,167
- 3
- 24
- 100
49
votes
14 answers
Almost half a million, yet smaller than a hundred
Consider, for example, the number 420109. It's quite big, isn't it? Not so far from half a million. Yet it can be interpreted to be smaller than a hundred with a very simple trick, without putting any mathematical operators between the digits,…
vsz
- 1,702
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49
votes
9 answers
An untouchable time traveller
I'm needed by a doctor to travel through time,
Or a player looking for their keys.
When on the plane where the great answer resides,
I'm part of the whole Strategy.
I can be found in a dead man's hand.
Yet still, I cannot be touched.
In…
hexomino
- 135,910
- 10
- 384
- 563
49
votes
4 answers
Rock, Paper, Scissors and Trump
Alicia and Robert are two high-stakes gamblers who are playing a match of rock-paper-scissors. Each winning throw is worth 10 €, paid by the other player. These players have deep pockets, so matches can last a long time and proper strategy is…
Jafe
- 78,615
- 8
- 162
- 614
49
votes
4 answers
Five Slitherlinks
Solve five Slitherlinks, each with a unique solution.
Please say a word regarding (or show an image depicting) each solution method.
DyingIsFun
- 9,176
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- 74
49
votes
2 answers
A crossword to appease all
(Click for full size)
Across
1. Steal extremely experimental metal song or 26-across maybe (6)
4. "Wardrobes malfunctioned", most rang for short interval (8)
10. Future engineer edits New York, USA's voting time? (7)
11. Plain type distraction…
Sp3000
- 7,527
- 2
- 27
- 60
49
votes
4 answers
Chess : The Lone King
An arbiter is trying to figure out what happened on the above adjorned game. He only knew that black made 15 moves and there can be more than one line of moves for this. Can you replay at least one game history for the arbiter?
TSLF
- 6,656
- 13
- 34
49
votes
10 answers
Clever Jack - A logical fairy tale
As so often happens in fairy tales, there once was a king who had an intractable problem, one that even his wisest advisers could not solve. After many years of frustration, the exasperated king eventually declared that any who could solve his…
crcroberts
- 1,833
- 15
- 18
49
votes
4 answers
I don't know the two numbers... but now I do
Two perfect logicians, Summer and Proctor, are told that integers and have been chosen such that 1 < < and + < 100. Summer is given the value + and Proctor is given the value ⋅ . They then have the following conversation.
Proctor: "I…
durron597
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