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1500 questions
36
votes
3 answers
Unsolved Mysteries: Magic Square of Squares
This is the first in what will hopefully be a series of Unsolved Mysteries posts.
Note that this puzzle has no known solution, nor any proof that a solution is impossible. We will see how smart the denizens of Puzzling.SE actually…
GentlePurpleRain
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36
votes
9 answers
Thirty genuine and seventy fake coins
In the country Curgonia, there are many types of fake coins and only a single type of genuine coins. The weights of these coins satisfy the following conditions:
All genuine coins have the same weight
Every fake coin is heavier than any genuine…
Gamow
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36
votes
4 answers
Expert puzzler, apprentice movie-maker
During rand al'thor's unscheduled sabbatical from Puzzling, he's managed to keep himself busy. How, you ask? Why, by making movies, of course! Unfortunately, our resident Puzzling expert is not quite as adept at movie-making, so he's stolen a few…
Bailey M
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36
votes
11 answers
Connect 3 houses with 3 wells
Connect every house with every well without the lines intersecting.
I am not sure if this puzzle has a solution. I have been puzzled by it for a long long time. An old man from my village mentioned this puzzle to me 12 years ago. I have never been…
Nermin
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36
votes
12 answers
Find the liar in the library
I've just taken a CS exam, which had the following question
6 persons entered a library the day a book got stolen. Each of them entered the library once and only once, and stayed there for some time, then left. If two persons were in the library at…
Gabriel Romon
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36
votes
1 answer
36
votes
2 answers
An Infinitude of Deceptive Devourers
Here's an original puzzle by me. I hope you enjoy!
A mother had infinitely many children, with the following names:
$\text{Albert}_1$, $\text{Albert}_2$, $\text{Albert}_3$, … , $\text{Beth}_1$, $\text{Beth}_2$, $\text{Beth}_3$, … ,
$\text{Clyde}$,…
Gavin Dooley
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36
votes
1 answer
Imagine a chess board, but seven-eighths wide
My grandfather wrote me this riddle on a napkin when I was 12. It took me more than a year to solve, but I got it eventually. He said I didn't get it until I had explained the sections, so explain every line.
Imagine a chess board, but…
Noah Smith
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36
votes
1 answer
Go mad with this one-dimensional jigsaw
E_E_E
R__HIN__O
GO__MAD
T_O___OTH
B_____E_N_T
SS_S___S
G__U_____N
HING_E
A_L___LE_Y
W___H_O
HO___T
R_UG
F_____I_G
N___UT
H_P
U__VA__R
TH___O_____N
YT
D_______V
SlowMagic
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36
votes
6 answers
36
votes
3 answers
A torus maze™™™™™
Since this is a torus maze, the left side of the maze connects to the right side and the top of the maze connects to the bottom. Corresponding openings in the walls of the maze have been labeled for your convenience.
Your goal is to get from the…
thesilican
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35
votes
6 answers
too easy puzzle? Try it first!
Arrange the numbers $1$ to $9$ to replace letters $A$ to $I$ so:
$(A+B+C+D)-(E+F+G+H) = I$
Too easy? Too many answers? Try it first!
Then explain why.
Jamal Senjaya
- 17,864
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35
votes
1 answer
MASTERING Sudoku
Fill the grid with letters M, A, S, T, E, R, I, N and G.
Standard Sudoku rules apply.
Additionally, the words on the right-hand side must appear in the given orientation (across/down). Each word must be contiguous (e.g. SNEAG doesn't count as…
cardboard_box
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35
votes
8 answers
Living next door to Alice
Bob and Charlie live in a small village with 99 houses, numbered from 1 to 99.
One day they meet Alice, a person who has recently moved to this village.
Bob asks her if her house number is a square number, and Alice answers his question.
Bob asks…
ThomasL
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35
votes
1 answer
Dissecting the exotic bulbfish
Can you cut the following black shape into exactly three pieces,
and then rearrange those pieces into a square?
plasticinsect
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