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.
52
questions with no upvoted or accepted answers
16
votes
0
answers
2k
views
What does this mathematical operator do?
The solution to this puzzle is one I came up with when working on this puzzle: What is the answer of this math puzzle?
For two natural numbers a,b, can you figure ...
- 552
14
votes
0
answers
1k
views
12
votes
0
answers
696
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 ...
- 627
10
votes
0
answers
598
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, ...
- 6,418
10
votes
0
answers
479
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,
...
- 2,296
9
votes
1
answer
674
views
Powerful number systems
Imagine I have two positive integers, $a$ and $b$. Can you find the last digit of the sum $a+b$ given only the last digits of $a$ and $b$? More generally, can you find the last $n$ digits of $a+b$ ...
- 441
8
votes
0
answers
272
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 ...
- 7,006
8
votes
0
answers
352
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 ...
- 2,349
8
votes
0
answers
194
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.
- 273
7
votes
0
answers
300
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 ...
- 71
7
votes
0
answers
387
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 ...
- 1,016
6
votes
0
answers
193
views
In an infinite maze of squares with p% walls, will you be boxed in?
If you are in an infinite maze of squares, where each border between two squares has a $p$% chance of being a wall, what is the probability $F(p)$ that you are trapped in a finite space?
For a better ...
- 161
6
votes
0
answers
182
views
Can you construct a nonagon with 47 rods?
Stiv's Diabolical Instruments now offers a bundle of exactly 47 equal-length rods that can be joined by hinges at their ends – and only the ends – to form planar linkages (i.e. all hinge axes are ...
- 7,006
6
votes
0
answers
367
views
6
votes
0
answers
544
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:
...
- 350
6
votes
0
answers
295
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.
...
- 61
5
votes
1
answer
161
views
Add as few plus signs as possible to make equation true
To allow new users to solve this puzzle and earn reputation points, I encourage all users whose reputation is 200 or more to not post an answer until 48 hours after this question is posted. Thank you!
...
- 5,956
5
votes
1
answer
231
views
What are the next 3 terms: 19, 43, 59, ...?
What are the next 3 terms in the following finite sequence?
19, 43, 59, 23, 79, 83, 109, 463, 569, 263, ?, ?, ?
- 33.4k
5
votes
0
answers
236
views
Longest Fibonacci word
Fibonacci words are defined as $F_0 = a, F_1 = b, F_{n+2} = F_nF_{n+1}$ where $a, b$ are letters. How can you find the longest Fibonacci sub-word in a given string?
Try to solve it in linear time ($O(...
- 51
5
votes
0
answers
176
views
Connect dots on a grid with one continuous line (optimization)
(This question is the third puzzle of the Connect dots puzzle series. You can find the first two puzzles here and here, respectively.
The original question and photos originate from webadventurer. ...
- 1,153
5
votes
0
answers
256
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, ...
- 624
4
votes
0
answers
227
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 ...
- 8,010
4
votes
0
answers
289
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 ...
- 6,418
4
votes
0
answers
155
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 ...
- 1,699
4
votes
0
answers
209
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, ...
- 1,573
4
votes
1
answer
542
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 ...
3
votes
0
answers
152
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 ...
- 821
3
votes
0
answers
237
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 ...
user73244
3
votes
0
answers
141
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
- 31
3
votes
0
answers
149
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.
...
- 647
3
votes
0
answers
216
views
Find Relation between the following numbers
If:
$23×3=76$
$13×3=26$
$3×3=9$
$33×3=70$
Find $43×3=?$
- 241
2
votes
0
answers
37
views
How to define "edge orientation" on a pyraminx?
I have a question about the pyraminx twisty puzzle. I've included a bit of background to make sure we're all using the same words.
(background)
To the initiated, a pyraminx is a triangular-looking ...
- 141
2
votes
0
answers
178
views
Do puzzles like "write 120 using four 8" have a specific name?
Here on puzzling SE there is the category "calculation puzzle", but it's very broad. I'd like to know if somebody gave a specific name for such puzzles.
- 2,087
2
votes
0
answers
109
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 ...
- 4,261
2
votes
0
answers
283
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|...
- 45
2
votes
0
answers
513
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 ...
- 1,699
2
votes
0
answers
242
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 - ...
- 21
2
votes
0
answers
350
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 ...
- 29
1
vote
0
answers
99
views
Can you find the missing letters?
A pattern of letters has had letters 10 through 20 deleted. Your job is to find out what letters should go in spots 10-20. Here is the pattern:
a, b, c, d, d, d, f, e, f, _, _, _, _, _, _, _, _, _, _, ...
- 111
1
vote
0
answers
192
views
The Angel Problem - Sticker Devil Variation
So If you are aware of the angel problem, I propose a Variant:
we introduce the Sticker Devil: A normal devil, with the added ability to sacrifice his turn to color any and all White Tiles that are ...
- 11
1
vote
0
answers
155
views
What is the value of x? 16-48-98, 32-->x
What's the value of x? (Original picture)
4
|
8--8--1
16-48-98
| |
32--->x
I have four possible answer choices: 130, 132, 160, and 260. I'm not sure which ...
- 121
1
vote
0
answers
443
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 ...
- 8,010
1
vote
0
answers
126
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 "...
- 8,079
1
vote
0
answers
606
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 ...
- 2,758
1
vote
0
answers
120
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 ...
- 111
0
votes
0
answers
203
views
mathematical puzzle whose solution seems to contradict its own hypotheses
This youtube video shows a mathematical puzzle that had me quite baffled, and at the moment I seem to disagree with the solution that is proposed as unique.
A leaf is torn from a paperback novel. The ...
- 203
0
votes
0
answers
111
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 ...
- 2,229
0
votes
0
answers
141
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 ...
- 9
-1
votes
1
answer
212
views
Poem coding scientific constants
The following Vogon poem contains various mathematical, scientific and cosmological numbers. There are ten. Can you find them? Credit for partial solutions.
A BTAUJV BTA ALEJM AV EUMJM FAV EATR O
- 738
-5
votes
1
answer
110
views
What is the number after 19? 1,4,8,13,19
It's a question on the application for my it certification school
