Questions tagged [puzzle]
For questions about the mathematical principles behind puzzle, games, riddles, or their possible solutions. Questions that are not strictly mathematical in nature should be asked on Puzzling Stack Exchange.
3,445 questions
0 votes
1 answer
48 views
In the limit, what probability of tails maximizes the expected number of shorter runs of heads followed by a longer run of tails.
We flip a coin $n$ times. The probability of tails is $p$. Let $X$ be the number of occurrences of a run of heads followed by a longer run of tails. We can also agree that if the sequence begins with ...
1 vote
1 answer
86 views
how to win the $100$ game?
Two players, $A$ and $B$, play the following game. Player $A$ chooses an integer $x$ between $1$ and $10$. Then, starting with player $B$, the players take turns adding to $x$ any integer between $1$ ...
-1 votes
1 answer
80 views
What is the minimum number of line segments required to split a rectangle into the 12 free pentominoes?
Let $R_{m,n}$ be an $m$x$n$ rectangle where $m$ is the width and $n$ is the length, and $R_{m,n}$ is subdivided into a grid of unit squares. A line segment is a horizontal or vertical segment drawn ...
0 votes
1 answer
51 views
What's the minimum number of sets in which you can tile all asymmetric n-ominoes into a non-trivial symmetric shape?
For clarification, s sets of all asymmetric n-ominoes means s copies of each of the k asymmetric n-ominoes. Non-trivial means that for $n = 5$, you can’t take the F, L, P, N, Y pentominoes and do this ...
4 votes
1 answer
75 views
What is the smallest rectangle tileable by copies of each n-omino that can tile a rectangle?
If the wording of the question was a little confusing, here is the main idea: Some $n$-ominoes cannot tile rectangles. We are excluding those. Excluding those $n$-ominoes not tiling any rectangle, ...
2 votes
0 answers
85 views
Can the unit disc be covered by seven squares, each of area one-half?
Some context and motivation for this question: A friend posed to me the following puzzle. Given eight points in the unit disc, why must there exist a pair of points with distance less than $ 1 $? The ...
3 votes
1 answer
43 views
What's the minimum number of sets of n-ominoes needed for it to able to be tiled into a rectangle?
For any $n$, what's the minimum number of sets needed for all free $n$-ominoes to be able to be tiled in a rectangle? For $n = 1$ and $n = 2$ the answer is 1 as there is only one monomino and domino. ...
9 votes
1 answer
694 views
A riddle involving the difference between lcm and GCD
I just read this riddle which i find quite interesting: Two friends are staying at the same hotel. While chatting in the lobby, one says to the other: "The difference between the least common ...
3 votes
0 answers
59 views
Generalized sliding-block puzzle
Finding solution of a Sliding Puzzle of size $N \times N$. asks about solving a sliding-block puzzle with multiple holes. Apparently a 2-hole puzzle is always solvable; as those who've played with the ...
16 votes
3 answers
1k views
Minimum # of black squares to guarantee uniqueness of loop visiting all white squares
I believe context will help before the statement of the problem. I was asked In the picture below, can you find a closed, non-intersecting loop visiting every white square exactly once? (If you do, ...
8 votes
2 answers
261 views
Adapted Kontsevich "Pebbling a Chessboard" game: can you win it?
In 1981, Kontsevich proposed the following problem. Imagine a chessboard that extends infinitely in only two directions: upwards and to the right. Put one pebble in each colored cell of the figure (...
3 votes
0 answers
97 views
Logic behind shuffled order of pages
I am exporting slides to pdf at an Optoma interactive touchscreen display I use in my lectures. The order of pages in the exported pdf is shuffled and I am trying to understand the logic how the ...
5 votes
1 answer
207 views
(Hidden) symmetries examples in probability
I am looking for some probability problems in which there is a symmetry that you don't notice in the first place, but by noticing it, you can easily get the answer. I have two examples in mind, and in ...
8 votes
3 answers
238 views
Which dates have Month-Day-Year and Day-Month-Year representations that are perfect squares? (eg, Sept 27, 2025: $9272025=3045^2$, $27092025=5205^2$)
Happy September 27th, 2025! A good friend of mine, let's call him Bob, wrote to me today with an interesting tidbit. Write Sept. 27th, 2025 in Month-Day-Year notation to get 09/27/2025. If you remove ...
1 vote
0 answers
72 views
How can I count the number of possible assemblies of a 32-piece puzzle given an adjacency list?
I am working with a physical puzzle consisting of 32 unique pieces. Each piece can only connect to certain other pieces, and all pieces must be connected together into one single assembly. There are ...