Questions tagged [mathematics]
A puzzle related to mathematical facts and objects, whose solution needs mathematical arguments. General mathematics questions are off-topic but can be asked on Mathematics Stack Exchange.
5,504 questions
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5 teams, 5 (?) games, how many rounds?
I am trying to come up with a rotation schedule for our company "Olympics". There are going to be 5 teams. There can be 3, 4, or 5 games depending on what works best mathematically. There ...
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Another Ping Pong Mystery
After digging around the courtyard some more, you stumble upon another weathered scrap of paper that was used to record the results of a few rounds of ping pong. The three players, Anne, Hartley and ...
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Nightriders ("long" knights) on a large chessboard
You can attack this question in a clever, in a general or in a bonus way.
Source is a chess problem of mine (yep, they publish math chess problems in the SCHWALBE, they have a whole category and mine ...
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What is a Short Integer™?
No, a Short Integer™ is not a Short Integer!
If an integer conforms to a special rule, I call it a Short Integer™.
Each integer can be tested. This is not a definitive list of Short Integers™.
Short ...
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Chess Heroics (Circle geometry)
The White Rook is boasting again.
"Fear me, puny Blacks! I came a long way from my home to punish you all!
First I killed a laughable Pawn. Then I made a right turn and a longer
move, and a ...
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2
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Minimum Crossed Knight Chess Tour
The Knight's Tour is a famous sequence of moves in a Chessboard.
We now search for a Knight Tour such that the number of intersections drawn by the tour is minimal.
Here is a valid Knight tour given ...
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Moving water by repeated equilibration
There are 100 full water tanks and 100 empty ones. You are given a hose that can connect any two of them in order to equilibrate the water level between them. All the tanks are cubical in shape, of ...
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Fill the wedges so that numbers in adjacent wedges differ by 1 or 2
Beginner puzzle (suitable for people who are new to puzzle solving).
Fill each empty wedge with a number so that:
all the numbers 1, 2, 3, … 12 each appear exactly once
and the numbers in adjacent ...
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2
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Chess - Amazons - Magnus Carlen vs Gukesh 2025 Norway
Parts of this puzzle are taken from this nice puzzle of @Will.Octagon.Gibson.
An Amazon is a fairy chess piece that can move like a queen or a knight.
In this famous game at Norway in 2025, ...
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Area of polygonal ring with only one measurement
Inspired by this question by RDK.
A polygonal ring is formed by two concentric regular n-gons whose vertices are radially aligned (shaded blue in the figure below for n = 5). You have a calculator ...
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Get ready for some multiplication!
As the title says, get ready for some multiplication! The answer is a word.
?? = _ _ _ (divisible by 9)
?? = _ (odd)
?? = _ (divisible by 3)
?? = _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
?? = _ _ _ _ _ ...
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Missing Game Archive 1 - What was the number?
This puzzle is one of the Missing Game Archive Series, which is my first PSE series. This series is about guessing the missing pieces in the game archive. Have fun!
» Next puzzle: Missing Game ...
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Aha! Diamond sum
With a suitable aha! moment, this puzzle can be easily solved in your head without knowing any formulas such as the sum of the first N positive integers.
What is the sum of the numbers in the ...
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3
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Area of the coloured regions in a unit square
A unit square is divided into infinitely many regions as shown in the figure below. The orange region is half the size of the red region, the yellow region is half the size of the orange region, and ...
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All Europe Countries Segmented
This puzzle is an attempt of improvement to my previous closed and poorly described puzzle.
You are given the following map of Europe:
And the following list of 50 Europe countries:
Albania
Andorra
...
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All countries segmented [closed]
You are given a 2 dimensional world map of all the countries (it can not be on a sphere), dated in the 21st century (no dinosaur map allowed!), large enough so that a human can distinguish France and ...
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Coins in Pockets 3 - Cough Up!
A follow-up to Coins in Pockets 2. Differences to that puzzle in bold.
The strategy will probably be based on the solution to that previous puzzle - you might want to try it out first (or just focus ...
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Coins in Pockets 2
This is a follow-up to Coins in Pockets
Again, N persons are sitting around a camp fire. They have a total of C coins in their pockets (each person having an integer amount of coins), with C < N/2. ...
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Name of an actress was blocked by a filter; Can you guess who is the actress
Note: I created this puzzle.
I was going to type my favorite actress in a post. But the filter blocked it, so I have to make some other way to circumvent the filter.
Because of that, I have to post ...
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Make 147896325 = 523698741 by adding as few as operators as possible (Another one)
This equation is false. Make it true by adding as few operators as possible:
147896325 = 523698741
Only the operators + - ...
user106806
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1
answer
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Minimize number of tiles to make hexagon packing stuck
The question Maximize the number of triangular tiles that can fit inside a hexagon after three tiles are placed shows a tiling puzzle where you have 18 triangles with angles of (30,120,30) that need ...
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Maximize the number of triangular tiles that can fit inside a hexagon after three tiles are placed
While traveling in Europe recently, I bought a tiling puzzle for my daughter. (It is a Grimm’s wooden puzzle, exactly like the one in this link.) The puzzle contains 18 congruent tiles, each of which ...
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Largest area enclosed by pentominoes
What is the most number of empty cells that you can enclose by placing each of the 12 pentominoes on a grid? Pentominoes can be flipped and rotated. An empty cell is considered enclosed if there is no ...
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Largest area enclosed by tetrominoes
What is the most number of empty cells that you can enclose by placing each of the 5 tetrominoes on a grid? Tetrominoes can be flipped and rotated. An empty cell is considered enclosed if there is no ...
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7
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Pythagorean Octagons
I have been revisiting Pythagorean Polygons, first posted by Florian F as Pythagorean Pentagons. I have solutions for regular polygons with up to ten sides and would like to see what others can come ...
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