All Questions
27,772
questions
4
votes
1
answer
111
views
A Professor's Presentation
Me and my three rich programmer friends who also happen to be very clever have these real life puzzle games from time to time. This time I am the creator.
I told them to visit a different country ...
- 37.3k
6
votes
1
answer
217
views
Colombian Sudoku, Cows and Bulls again…
Fill the sudoku on the left so that each column, row, box, and colored box of the same color contain the numbers 1 to 9. The dots show how many numbers in the row or column of the grid on the right ...
- 613
2
votes
2
answers
316
views
Knights, Knaves, and Spies
I need help understanding this problem. I keep thinking about it and haven't found a solution fitting to it. If you could help me that would mean a lot, Thank you.
An island has three kinds of ...
- 21
6
votes
1
answer
216
views
Impressions – a cryptic crossword
Solve on Penpa+
Across
1. Past prog rockers (RIP) drinking whisky (10)
6. Acting award for Mr Hopkins, according to inside source? (4)
9. Clean up after last bit of tofu remaining on plate, perhaps (7)...
- 78.8k
-1
votes
0
answers
87
views
Alternate Blue Eyed Island Conclusion - Contradictory Laws
In the 100 blue-eyed islanders riddle, there is a rule that if an islander figures out his eye color, he must leave the island. Doesn't that contradict the other rule that he can't inform anyone else ...
4
votes
2
answers
229
views
Maximizing row and column products in a 4x4 grid
Using the numbers 1, 2, 3, ... 16 each exactly once, fill each square of a 4x4 grid so that the product of the numbers in each row is a multiple of $N$ and the product of the numbers in each column is ...
- 13.4k
4
votes
1
answer
566
views
Determine if N is zibbable
The Zib sequence ${Z_N(M)}$ = $\{{a_i}\}$ is a very simple sequence defined on a pair of numbers $N \in \mathbb{N_{odds}}$, $M \in \mathbb{N}$:
${a_0}$ = $M$
${a_{i+1}}$ = $a_i+N$ if $a_i$ is odd
${...
- 891
-6
votes
0
answers
64
views
How to rotate ten players? [closed]
How to rotate ten card players over two separate tables as equal as possible for four different games?
-2
votes
0
answers
106
views
Are the Polybius cipher and the Bifid cipher really easy to solve?
I looked up those two ciphers and decided to make a twisted combination of them, here are some of the steps I followed:
use the bifid cipher;
go to the RIGHT by 2 on AZERTY keyboard (on B and N go ...
1
vote
0
answers
80
views
Can black and white cooperatively put a stalemate to black in 16 moves (under ser-h conditions)?
ser-h=n – serial helpstalemate in n moves. Black execute n moves in a row, after that White execute a stalemate for bK.
Additional questions:
a) how many stalemates are possible under the same ...
- 189
2
votes
1
answer
211
views
Largest prime number erroneously erased when finding all primes less than 1000
Chicharron is a lover of mathematics and once wanted to find all primes less than 1000. He did by the following steps below:
He wrote all the numbers from 2 to 1000.
He circled the number 2 and ...
4
votes
2
answers
393
views
Can white checkmate in 1 move?
How can this position be reached (via a valid chess game) so that white can checkmate in 1 move?
S.Nichto,2024
If desired, you can answer additional questions:
a) the minimum number of moves in the ...
- 189
16
votes
1
answer
1k
views
5
votes
1
answer
562
views
What were the last three single moves?
Puzzle by Niels Høeg:
White just moved. What were the last three single moves? In other words, what was White’s last move and Black’s move before that and White’s move before that?
- 13.4k
11
votes
2
answers
2k
views
