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.

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CSE Hex Cube Puzzle

I've been tackling this puzzle named "Hex Cube" from the CSE (Communications Security Establishment, the Canadian "equivalent" of the NSA) which comes with the instructions: "...
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  • 181
12 votes
0 answers
1k views

How would this binary-ish code be translated?

...
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11 votes
0 answers
458 views

Dissecting a figure into 2, 3, 4, and 5 parts but not 6

This figure is divided in 2, 3 and 4 equal parts of same size and shape, but it is not possible to do it in 5 equal parts of same size and shape. Is it possible to find a figure that can be divided ...
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10 votes
0 answers
148 views

Rigid regular nonagon from 21 Meccano strips

You are given 21 Meccano strips, where the distance between adjacent holes is 1 unit: 9 strips of length 10 (hence having 11 holes) 6 strips of length 18 (19 holes) 6 strips of length 19 (20 holes) ...
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  • 3,906
10 votes
0 answers
439 views

Dead By Daylight

This puzzle is a reference to a game, Dead By Daylight. Though you don't need a knowledge about the game. Consequently, there is no "video-games" tag. Story The Entity wants to have the ...
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  • 3,329
10 votes
0 answers
443 views

I'm a number with a special product, so name me when you think you've got it

In the blocks that come before, their special product tells us more. To guess my scheme you'll need calculation, but only little tests of recreation. Each block contains atoms strong as Thor, ...
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9 votes
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499 views

Gold and silver coins in sealed envelopes

Alice has freely chosen to put either a gold coin or a silver coin in each of an infinite sequence of envelopes numbered 1,2,3,... Bob can open any number of envelopes and check the coins within, ...
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9 votes
0 answers
435 views

Can Alice form a unit square?

Alice and Bob take turns to mark points in $\mathbb{R^2}$ (i.e. infinite 2D plane). Alice can only mark $1$ point on her turn, while Bob can mark $N$. They're free to mark their points anywhere as ...
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8 votes
0 answers
239 views

Doubling the cube with rational Meccano strips

In three monographs published in 2006, 2008 and 2014 Gerard 't Hooft considered "Meccano mathematics": how to construct specified distances and regular polygons by a rigid system of ideal ...
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8 votes
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326 views

A Glutton and a Split Check

N, T, A, B are arbitrary constants in this problem. I have only definitively solved the N=1 subproblem, so, if the general problem cannot be solved, I will be satisfied to mark as accepted a solution ...
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  • 1,768
8 votes
0 answers
181 views

Is it possible to create a knot that is locked only when the rope is stretched?

Is it possible to create a knot that is stable/locked when the rope is stretched? When the tension is relived the knot should open.
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7 votes
0 answers
373 views

Open the French safe

While walking in a small alley in Paris, you come across a safe. The number pad looks like this : There are things on the back of the safe too : "À l'aide du carré 3x3 ci-dessous et des nombres ...
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6 votes
0 answers
312 views

Turn the dials until each of the 12 columns add up to 42

I received the wooden puzzle below for Christmas. After playing with it for a while I decided I needed to actually write something down if I was going to solve it. Eventually I just wrote an algorithm ...
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6 votes
0 answers
340 views

Try to solve the “Mexican Puzzle”?

Can you solve this puzzle I created last week?
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6 votes
0 answers
271 views

Even and primes puzzle?

These are secret numbers that increase regularly. What are the next two numbers? If you like numbers, it will be fun. $2^3 \times224299$ $2^2 \times 3^2 \times 19 \times 3557$ $2 \times 5 \times ...
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  • 61
6 votes
0 answers
222 views

The Abnormality of me

I just got born. There's nothing I can do. Maybe "nothing" is such an appropriate word for an age 0. A year passed. There's still nothing I can do. I haven't changed. Maybe I am to retain my ...
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6 votes
0 answers
535 views

Locked Door Number Puzzle

I'm supposed to make a delivery to a crazed botanist. In case you're curious, the shipping manifest is: ...
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6 votes
0 answers
286 views

Find the missing element?

I've been trying to solve this for quite some time, can you help me solve it? This puzzle was made by one of my friend's teachers. This is not copyrighted and cannot be found anywhere on the internet. ...
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5 votes
0 answers
179 views

What is a Good Pasta Number™?

This puzzle is inspired by JLee's What is a Word/Phrase™ series and the subsequent "Number" variants. (Actually, I'd originally tried to create a more original puzzle using the same idea, ...
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4 votes
0 answers
267 views

One vs many. Can white force a draw?

On an infinite chessboard there's a single white king and N black kings. The nearest black king must be K moves away from the white king. Given N, white dictates the value of (finite) K, then black ...
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4 votes
0 answers
150 views

Ideas on spatial puzzles for a city walk

Background. With the relaxation of covid-related restrictions, there was a need for intelligent city walks. Walk here is a moving between city objects by a certain (deterministic/stochastic) route. I ...
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4 votes
0 answers
196 views

The madness of a master

It was midnight. Mr. Holmes was suffering from abdominal pain, shortness of breath, pain in the bones, skin lesions and whatnot? So in this condition, why would Mr. Holmes drive to Brazilian Churches, ...
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4 votes
0 answers
205 views

Find Relation between the following numbers

If: $23×3=76$ $13×3=26$ $3×3=9$ $33×3=70$ Find $43×3=?$
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4 votes
1 answer
516 views

Formula for the sequence 1, 1, 1, 21, 3, 1, 4, 1, 5, 1, 6, ... if the 21 isn't a mistake

The sequence 1, 1, 1, 21, 3, 1, 4, 1, 5, 1, 6, ... appeared in one of my tutorial sheets in 2019. I assumed that the fourth term, 21, was a mistake (was supposed to be ..., 2, 1, ...) then it made ...
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3 votes
0 answers
208 views

The smallest number

Some time ago I created a program to generate a table, and printed the first seven rows and columns. Somehow however I forgot to print the headers and the title of the table. I only remember that it ...
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3 votes
0 answers
266 views

Find a missing number in this 28x21 grid

355|066|677|855|677|081|044|855|355|062|216|677|216|855|224|044|034|046|051|677|355|264|044|046|044|351|886|043 043|044|886|357|886|352|225|357|043|222|993|001|233|968|046|225|062|041|351|886|043|227|...
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3 votes
0 answers
139 views

A math-based jigsaw

This is a fun puzzle I invented 50 years ago. ("Loops of Zen" is rather similar, idea-wise.) Here is a random solution (doesn't spoil much)... ...and here are the building blocks: Basic is ...
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3 votes
0 answers
456 views

Fill in a 5x5 multiplicative magic square

Let's say you fill in a 5 by 5 square with the numbers 1, 2, ..., 25. Is there a way to fill it so that the product of the first row is equal to the product of the first column, the product of the ...
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3 votes
0 answers
216 views

Infected Cylinder and Torus

A variant of the well known Infected Checkerboard problem. If we've a 𝑛x𝑛 square, then we fold it along top and bottom row to form a cylinder. A cell in this cylinder becomes infected if at least ...
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3 votes
0 answers
131 views

Does anybody know the history of this star/triangle puzzle?

Does anybody know the history of the puzzle posted by Mario Bilotti? Who created this puzzle? Who deserves the credit? Find 10 triangles in a five pointed star using two straight lines
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3 votes
0 answers
146 views

The Game of Numbers (#02)

Related to The Game of Numbers (#01) Agatha just decided it still isn't enough because she thinks it's way too easy. She decides to add one more rule to the list and change some of the existing rules. ...
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2 votes
0 answers
53 views

Three planes fuel tanks for less than halfway around the world - how can one plane make it around the world and what is the minimum fuel tank size?

Inspired by this recent question here is a variation. Three identical aeroplanes are based on an island with one airport. Each plane can take fuel to get less than halfway around the world. Fuel can ...
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2 votes
0 answers
123 views

Maximize my flags - 2x2 version

Because Maximize my flags was not solved to optimality by the community, perhaps because the coding required was too harsh, I present you Maximize my four flags. The rules are exactly the same as in ...
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2 votes
0 answers
417 views

Not a sudoku, but still fun?

Context: I was trying to solve some of the puzzles on this site, when it occurred to me to make a puzzle variant myself. I immediately could construct one with my additional rule. Making an ...
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2 votes
0 answers
492 views

A robot moving on a grid. Part 2

This is an extension of the discussion A robot is placed on a grid point. At each move the robot must take three steps along the edge of the grid. After each step the robot must turn right. Lengths of ...
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2 votes
0 answers
237 views

Code Breaking ( Sort of )

So someone sent me this code breaking/riddle to solve and I got really confused on it. I do need help on it, The Code needs to come out into a Phrase ( group of words ) CLUE 1: 2210232013400 - ...
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2 votes
0 answers
304 views

ARG Puzzle Gate 15 Help

Me and my group (yes I'm in a group trying to solve this) are currently working on an ARG puzzle and we are stuck. The first image/clue to the entire puzzle is what is seen below. The creator of this ...
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1 vote
0 answers
241 views

She and I were born... And she's younger!

Ma copine est née le 4506760140210316 moins 4 et moi le 1085504342017368 moins 3. Which is French for: My girlfriend is born the 4506760140210316 minus 4 and I the 1085504342017368 minus 3. Tell ...
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1 vote
0 answers
118 views

Searching online catalogs is a pain. Can you tell me if it's worth my trouble?

Searching online catalogs is a pain. Can you tell me if it's worth my trouble? As an example, I searched the following online catalog of a well-known country-wide British outlet for the keyword "...
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1 vote
0 answers
600 views

Decode this message to stop the destruction of Science!

An extremist religious organization called "The Redeemed Against Scientific Usurpation of God's Authority", or RASUGA, have converted the world's leading time travel researcher to their ...
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1 vote
0 answers
118 views

Filling a sudoku/latin square like array

Let us build a square array in the following manner, which I would like to call a modified sudoku: 1) Every row and column contains only one copy of a positive entry and there are exactly $t$ such ...
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  • 111
0 votes
1 answer
144 views

Generalization of twelve balls and scale problem

This problem is a generalization of Twelve balls and a scale problem. So I can solve and understand how things are going if we have 12 balls or 9 balls but how do I generalize? If say we have $3^n$ ...
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  • 603
0 votes
1 answer
187 views

What is this card matching game/trick?

As a kid I used to do this card game/trick a lot but I can’t remember what it is or how to do it anymore. All I remember is that it used math or counting. You had a certain amount of cards sort of ...
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  • 1
0 votes
0 answers
105 views

Bisecting a 3D object into two equal volume objects - 2

Given the following 3D object and means of an unmarked ruler to draw lines on its surface define a straight cut that will split it into two objects with the same volume. Hint: It seems to have at ...
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  • 2,166
0 votes
0 answers
134 views

How Do You Prove That This Puzzle Is Physically Solvable?

https://www.reddit.com/r/BeAmazed/comments/fyt7x9/it_seems_to_be_impossible_but_it_gets_done/?ref=share&ref_source=link The goal of the puzzle is to remove the wooden stick from the jar by ...
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-3 votes
1 answer
319 views

Open dice Problem

The following figure is folded to form a box. Choose from the alternatives (A), (B), (C) and (D) the boxes that is similar to the box formed. Source: YouTube Video How to answer these type of ...
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  • 17
-9 votes
1 answer
242 views

Find the next number in the weird sequence

The following sequence has been made using a specific pattern and the last number is kept secret. We have to find that number along with the pattern followed to make the sequence. 3, 11, 32, 71, 136, ...
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