All Questions
22,353
questions
2
votes
2answers
38 views
Dividing the first 10 primes into groups whose sum is prime
Take the first 10 primes. Can you divide them into $g$ disjoint groups, such that the sum of numbers in each group is prime. In particular can you make this work for every value of $g$ in the range $[...
5
votes
1answer
44 views
A borrower but not a lender be, I'm not a bank or university
From me you can borrow, but only for a while.
You've got to give it back or you'll pay a debt.
I won't borrow from you, that's not my style.
But you can give to me and some money you'll get.
I'm ...
7
votes
0answers
84 views
A Cryptic Property
An entry in Fortnightly Topic Challenge #48: Unusual tag mix
After solving the following cryptic clues, find the following properties:
A major property that all ten words share.
A minor property ...
5
votes
1answer
134 views
TFS (strings of letters)
Complete the image below with the correct strings of letters in the correct squares (four squares will be left empty).
Transcription (■ is a square that does not exist in the image, and ? is a blank ...
7
votes
1answer
437 views
Doubly Pure Checkmate
A pure checkmate is a checkmate where for each square the king might go to, there’s exactly one reason it can’t. The famous Légal mate is one example, so is a KR vs K checkmate.
What’s the minimum ...
8
votes
2answers
306 views
A [prefix] at [infix] early [suffix] can't [whole] everything
A [prefix] at [infix] early [suffix] can't [whole] everything.
What is the logical statement when the gaps are filled?
1
vote
1answer
146 views
What letter comes next in the sequence A, P, I, W, A, T
What letter comes next in the sequence: A, P, I, W, A, T, ?
3
votes
1answer
48 views
A Final Digitial Sudoku! - SS#14
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
Other puzzles in this series
Welcome to the final puzzle in this series! For more information about the series, see the first ...
12
votes
2answers
468 views
Unequal Curfew - Donut Hole
This is a Curfew variant. Curfew is a genre invented by Hempuli; I made a slight modification to give this variant.
Rules of Unequal Curfew:
Draw a loop that visits every circle.
Each visit to a room ...
0
votes
1answer
84 views
Mirror Mirror On The Board
Mirror mirror in the board
Decipher the riddle of this horde
How many moves to it, please?
To put my brain at ease!
Both sides help, follow their paths
The solution you must craft
Oh, and there is but ...
14
votes
1answer
368 views
This Sudoku Park iS LIT!
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
The grid below is a normal Sudoku grid with normal Sudoku clues, but the completed grid also houses a Statue Park! The completed ...
1
vote
1answer
85 views
Why is 'logjam' the answer to 'function held up by traffic blockage'?
Why is 'logjam' the answer to 'function held up by traffic blockage'? I guess 'log' is function, and logjam is blockage but why 'jam/maj'? L,G & A are all correct.
12
votes
1answer
252 views
Sudoku: Odd Bonds
An entry in Fortnightly Topic Challenge #47: Wacky Sudokus.
Edit: Clarified three of the rules.
Rules:
Normal sudoku rules apply.
Inside the sudoku, there exists one "loop".
The loop ...
-1
votes
1answer
104 views
Heptagon, nonagon
What is the trick to constructing a heptagon and a nonagon which have all their sides equal? The length of the side has to be a natural number. Your answer should include a drawing of the two polygons....
0
votes
0answers
111 views
Help with a program to solve Einstein's Riddle [closed]
I have been trying to write a program (just for fun) to solve Einstein’s Riddle, see https://play.google.com/store/apps/details?id=com.rottzgames.logic.
My solution basically does this:
It creates an ...
7
votes
2answers
224 views
Cutting a shape into two equal area shapes
Given the following shape - an hexagon ABCDEF of which a parallelogram CDGH is cut out.
With a single cut divide the shape into two equal area shapes by means of an unmarked .
You may draw lines and ...
9
votes
1answer
206 views
A Fractal Sudoku - SS#13
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
Other puzzles in this series
Welcome to the penultimate puzzle in this series! For more information about the series, see the ...
13
votes
1answer
277 views
A No Sensa Test Question with Mediterranean Flavor
Which of the three options fit in the central Octagon which is common to the two diagonals, one vertical and one horizontal row? Separately, each diagonal row (Brown and Red boxes), the horizontal row ...
4
votes
1answer
115 views
Identifying the wooden puzzle-box featured in Tomb Raider
In the film Tomb Raider (2018) there is a wooden puzzle-box with rotating sections. Once the correct sequence of moves is performed, a drawer pops out. See here:
Upon seeing it she says:
Karakuri. ...
0
votes
3answers
83 views
5x5 grid with no tetrominoes containing repeating colors
Paint the cells of a 5x5 grid with 𝑛 colors, such that every possible tetromino found in the grid uses 4 different colors. What is the smallest value of 𝑛 possible in such a coloring?
Here is a ...
3
votes
3answers
340 views
4x4 grid with no trominoes containing repeating colors
Paint the cells of a 4x4 grid with 𝑛 colors, such that every possible tromino found in the grid uses 3 different colors. What is the smallest value of 𝑛 possible in such a coloring?
1
vote
0answers
115 views
Men of the past
J.R.R. wrote about the dragon, thinking of these men.
Issur performed and challenged the locals to do a crossing, thinking of these men.
G.R.R. wrote about the killer of the giant, thinking of these ...
2
votes
2answers
89 views
A number built with two-digit primes
What is the largest number, which can built as a sequence (from left to right) of different two-digit primes only?
For example, 1371731 is valid, 137131 is invalid (containing 13 twice), 139717 is ...
6
votes
1answer
150 views
Logic grid puzzle - Carson City Chronicle
I can't figure this one out. Any help would be appreciated.
Journalist-in-training Janet Seymour's byline appeared in the Carson City Chronicle on six days last week. On each day (Monday through ...
9
votes
1answer
423 views
Sudoku with no grid and no numbers!!? - SS#12
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
Other puzzles in this series
Welcome to the twelfth puzzle in this series! For more information about the series, see the first ...
10
votes
1answer
106 views
A full cryptic crossword
Eight clues are thematic and are clued by word-play only. Each of these eight clues' word-play has an extra letter which is not part of the answer. These letters cryptically indicate something, ...
20
votes
1answer
892 views
Sudoku in Technicolor!
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
This puzzle consists of three overlapping Sudokus, coloured red, blue and green, so each cell will contain three digits, one of ...
15
votes
2answers
2k views
Hotaru Beam Puzzle: Is it impossible?
I saw this puzzle on Twitter by user @lilva_0419 and I personally feel that it is impossible to solve. Can you prove me wrong (or right)?
Source on Twitter
Try it online
Rules (see Wikipedia):
...
1
vote
2answers
145 views
How to solve this 3x3 dots and lines puzzle?
I saw this on a forum and no one knows how to solve it, and it's driving me crazy. Does anyone know what the solution is and why?
I tried looking at similarities in the columns, rows, and diagonals. I ...
6
votes
1answer
626 views
Finding the median of 5 numbers
There are 5 boxes labeled A, B, C, D and E. Each box contains a distinct number, but you don't know what it is. You can select three boxes and the Oracle will tell you which box contains the median* ...
0
votes
1answer
91 views
10X10 Sudoku with a specific requirement
Let's have a 10x10 grid. We want to create a Sudoku in which, in each row, the pairs (a+b), (c+d), (e+f), (g+h), (i+j) add to one of the following numbers: 7, 9, 11, 13, or 15. Can you construct a ...
6
votes
3answers
527 views
Table of mathematical expressions - fill in 1-9
Fill in the numbers 1 through 9 in the 9 empty cells (each number appears exactly once) to make the row and column expressions equal to the number at the end of the row or column.
Regular math ...
4
votes
1answer
128 views
What is this puzzle with identical wooden pieces?
I received a bag of wooden pieces, but cannot figure out what the puzzle is supposed to be. I've tried several burr options and several Alketruse puzzles, but cannot find the correct configuration. ...
3
votes
2answers
77 views
A triangle inside a triangle
All sides of a triangle T1 are shorter than the shortest side of a triangle T2.
Is it always possible to put triangle T1 completely inside triangle T2?
7
votes
1answer
88 views
This Sudoku takes a step up! - SS#11
An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus"
Other puzzles in this series
Welcome to the eleventh puzzle in this series! For more information about the series, see the first ...
-4
votes
1answer
71 views
math quiz question to be a math teacher [closed]
If I have a multiple choice question where $\int_ {e} ^ {2e} \frac {x} {\ln(x)} dx $ is equal to:
a) 6.55...
b) 7.28...
c) 7.93...
d) 7.96...
e) 8.10...
f) 10.10...
the ... means that there is ...
-1
votes
1answer
86 views
Gaby's 21 students sitting around a circle [closed]
Gaby numbers her 21 students with the primes between 11 and 97. She now asks them to sit around a circle making sure that any two of them sitting next to each other have either their tens or units ...
3
votes
5answers
509 views
Ma turned 34 in 2002. Really?
My friend said to me:
“In February of the year 1970 at 1:12 AM Ma turned 18. Ma turned 34 in
February of the year 2002 at 2:16 AM. How is this possible?”
“And yes. Same Ma!” he ended with that.
Hint
...
-3
votes
1answer
234 views
Gold coins robbery [closed]
I am posting an interesting problem which I find in my local magazine named 'Dainik Bhaskar' in the riddles section. At first sight, I think this will be an easy one. But I am wrong. Can anyone help ...
0
votes
0answers
42 views
An orderly transition of power [duplicate]
Since it's the 20th of January, perhaps we can demonstrate an orderly transition from TRUMP to BIDEN?
There are eight steps to get there and all words are found in the World Scrabble dictionary. One ...
11
votes
2answers
150 views
-4
votes
1answer
85 views
How to open the lock from this safe?
The puzzle is as follows:
The figure from below shows a lock mechanism used to store sensitive
data microfilms from a certain lab.
This mechanism is magnetic and consists in numbered buttons which
...
-4
votes
0answers
61 views
How to get the least amount of pours to obtain a fractional amount of yoghurt?
The puzzle is as follows:
A dairy plant in Milwaukee is well known for its yoghurt. However
during the quality control a factory worker forgot to bring a set of
adequate vessels to measure the ...
0
votes
2answers
91 views
What do these three towns have in common?
What do these three towns have in common?
"Dublin", "Blackpool", "Chernobyl".
3
votes
2answers
435 views
How to fill 1/3 of the cylinder?
You are given 3 containers - pictured in this order below:
a box with side 2, height 1, and a cone with base radius 1 and height 1 in the middle.
a box with side 2, height 1, and a half sphere with ...
6
votes
1answer
176 views
I got [prefix] [suffix] [infix] from washing the [whole]
I got [prefix] [suffix] [infix] from washing the [whole].
P.S. I [infix] the [whole].
The note above, when the gaps are filled, will be a grammatical and reasonable note.
What is the note?
4
votes
4answers
345 views
How to get the least number of flips to a plastic chips to get a certain figure?
The puzzle is as follows:
(Transcription with grammar errors fixed)
A game consists of the following:
The challenge is to flip the chips in such a way so that they are as in state 2. You start in ...
6
votes
2answers
252 views
Pandigital fraction sum that evaluates to 1
Fill in the nine X spots in the following equation using each of 1, 2, ..., 9 exactly once, so that the equation is satisfied. The XX in the denominator denotes concatenation of two digits.
$$
\frac{X}...
3
votes
2answers
348 views
In the sea or in the sky
In the sea or in the sky
Sometimes also in your eye.
Melancholy feels like me
But energy I have plenty.
Into me you have vanished
Out of me you're astonished
What am I?
-4
votes
2answers
65 views
A challenge to make 1 - 100 [closed]
So this challenge is you have (don't have to) make the numbers 1 - 100 by using the numbers 1, 3, 4, 6 only once. I'm stuck on how to make 54. Can anyone help me?
P. S. You can use +, -, ÷, x, ! And ...