Unanswered Questions
67 questions with no upvoted or accepted answers
22
votes
0
answers
3k
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 ...
- 660
14
votes
0
answers
1k
views
12
votes
0
answers
454
views
Can we find four identically colored numbers?
Take the positive integers {1, 2, 3, ...} and color them red, green or blue. Is it true that no matter what coloring is chosen, we can always find three distinct numbers x, y and z so that x, y, z ...
- 16.2k
12
votes
0
answers
259
views
The Snake and the Hunter
The Snake and the Hunter is a game for two players who play in two rounds interchanging the roles of snake and hunter. The game is played in a rectangular grid of points, say 6×6. In both rounds the ...
- 19.3k
12
votes
0
answers
896
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 ...
- 886
10
votes
1
answer
752
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 $a+b$ ...
CommunityBot
- 1
10
votes
0
answers
512
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
0
answers
361
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 ...
- 2,389
9
votes
1
answer
2k
views
Is there another name for this puzzle? (Kyudoku, Nine Find)
Is there another name for this type of puzzle? I can only find two examples of it online:
https://www.brainzilla.com/logic/kyudoku/
http://ninefind.com/
In the game you start with a 6x6 grid filled ...
CommunityBot
- 1
8
votes
0
answers
277
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 ...
- 7,820
8
votes
0
answers
201
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.
- 8,333
7
votes
0
answers
197
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 ...
- 7,820
7
votes
1
answer
1k
views
Name and solution of puzzle to rotate all arrows to same direction
In this puzzle, when you click an arrow, all arrows immediately next to it (diagonally included), as well as the arrow you clicked itself rotate 90 degrees. The goal is to get all the of arrows to ...
CommunityBot
- 1
7
votes
0
answers
314
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 ...
- 6,581
7
votes
0
answers
397
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 ...
- 1,006
6
votes
0
answers
255
views
Visual puzzle involving mathematical operations
Try this puzzle. It involves mathematical operations. Created on my own.
CSV (for those who aren't able to see images):
...
- 2,423
6
votes
0
answers
207
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
291
views
Trying to find a 2020 puzzle hunt with a puzzle based on Among Us
I am trying to find a puzzle hunt that I believe was held in 2020. It contained a puzzle based on the game Among Us with 26 characters, and you had to decide who were the imposters. The imposters all ...
- 10.3k
6
votes
0
answers
375
views
6
votes
0
answers
314
views
Looking for a kid's puzzle, cannot remember title
I'm looking for a kids' logical puzzle I saw in a Brazilian puzzle magazine several years ago. A farmer had a square farm with four houses and twelve trees and he wanted to divide it between his four ...
- 35.6k
6
votes
0
answers
302
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.
...
- 41.7k
6
votes
1
answer
505
views
Late 18th/early 19th century numbers grid
I was researching an historical figure on the Isle of Man, Capt George Quayle (b.1751 - d.1835), and in amongst the museum's papers was this numbers grid which was part of his effects. The museum ...
CommunityBot
- 1
5
votes
0
answers
251
views
The null, quotes, and the completeness
Here's a riddle:
There are three base things: The null, Quotation marks (or simply, quotes), and the completeness.
The quotes inside destroy the null, and convert to quotes, and the quotes will let ...
- 185
5
votes
0
answers
265
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(...
- 151
5
votes
0
answers
264
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. ...
- 1,163
4
votes
0
answers
164
views
Wooden puzzle with multiple balls on strings attached to a central hook, from which metal arms connect top and bottom
I bought this puzzle few years ago at a market. I couldn't solve it since. I started to think it was wrongly assembled, therefore can not be solved. Tried to find the solution on the internet/YouTube ...
- 10.3k
4
votes
0
answers
251
views
Is there a name for crosswords where the surface of the vertical clues resemble the solutions to the horizontal and vice versa?
Occasionally a crossword (often cryptic ones) would have a twist to them, such as being a 'nina':
A Nina is a special feature of the crossword grid: a word, words or phrase hidden within a pattern of ...
- 6,000
4
votes
0
answers
234
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 ...
- 229
4
votes
0
answers
349
views
Do minecart puzzles like this, with buttons that rotate track, exist?
This is the end result of me messing around with minecarts and moving floors.
The buttons change the orientation of either their nearest or their same-color track. Now I'm not asking you to solve the ...
- 143
4
votes
0
answers
158
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 ...
- 18.9k