This tag is meant for questions about the mathematical principles behind games, riddles, or their possible solutions. If the answer is known to you please do not use this tag to "riddle" other users, but rather to ask about the correctness of a possible solution or ways to extend and improve an ...

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5
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1answer
99 views

Return of the lost ant 3D

Starting in the center of a sphere of radius 1, draw a path with the shortest possible length that intersects every plane that is tangent to the sphere. This question appeared as a generalization of ...
4
votes
1answer
104 views

How many answers to this combinatorial puzzle?

Take a square. How many ways are there to draw or not draw a line from the center to each of its sides? 16, of course. Here are all the different squares: Now, how many ways are there to put ...
4
votes
1answer
44 views

Limitations on orientations of a character on the surfaces of a cube

When looking at a cube you see either two surfaces across an edge or three surfaces around an apex. Is it possible to arrange a non-symmetrical character (e.g."R") at 0,90,180 or 270 degrees rotation ...
3
votes
1answer
132 views

Looking for a pattern in a math riddle

Looking to find a pattern but no idea how: $12\mathop{\square}21 = 86$, $13\mathop{\square}31 = 192$, $14\mathop{\square}58 = 389$, $14\mathop{\square}94 = \ ?$
3
votes
1answer
73 views

Minimal diameter of set of fractions

Let $p_n$ be a pairwise partition of $\{1,2,...,2n\}, n\in \bf N$ where $(a,b)\in p \implies a<b$, and $P_n$ the set of all such pairwise partition. $d(n) := \min_{p_n\in ...
3
votes
1answer
131 views

Smullyan-To-Mock-a-Mockingbird, Find egocentric bird in L

Question (29, p. 81). Let me tell you the most surprising thing I know about larks: Suppose we are given that the forest contains a lark $L$ and we are not given any other information. From just ...
2
votes
1answer
93 views

roulette wheel sequence

Is the sequence of numbers around a European roulette wheel (the integers from 0 to 36 inclusive) random or is there a pattern to it? It is said to have been devised by Pascal, which might be thought ...
2
votes
1answer
105 views

Weird system of equations

X : 2 = 7 Y : 2 = 6 X + Y = 15 Find X and Y. I think maybe this is some unpositional number system. I've tried positional, and it works for basis 21 (if we take X=D, and Y=C), but professor told me ...
12
votes
0answers
99 views

The Right Triangle Game

I am looking for a deeper understanding, particularly the optimum strategy and the maximum score as a function of grid size, of the following (single-player) game played with an $n$ by $m$ grid: ($6 ...
8
votes
0answers
659 views

Is the game 2048 always solveable?

Games got me on math. I always want to play best. I don't know how to answer my question. My question is : How to show that the game 2048 is (always) solvable>? Is there any method other than ...
5
votes
0answers
96 views

Card passing game, maximum length

Quoting from this question: There are 25 people sitting around a table and each person has two cards. One of the numbers 1,2,..., 25 is written on each card, and each number occurs on exactly two ...
4
votes
0answers
77 views

How many points you should draw in the square at least´╝č

There is a square, which side length is $2$, To ensure there exists a triangle in the square, with an area less than $0.5$, how many points should you draw in the square at least. the goal is for all ...
4
votes
0answers
112 views

Whats the mathematics behind this type of taking the rope out puzzle.

I know there has to be a way to solve this puzzle with math. I have included a picture, because I don't know the proper terms for this puzzle. I have included two pictures, I believe they are the ...
4
votes
0answers
281 views

A product puzzle

This is from a math contest. I have solved it, but I'm posting it on here because I think that it would be a good challange problem for precalculus courses. Also, it's kind of fun. Write the ...
3
votes
0answers
50 views

Given a number of items, how many sets of three are there where no two sets are two thirds similar?

Sorry if the title isn't proper math-talk. Hopefully I can explain it better here. So let's say we have a set. 1, 2, 3, 4, 5, 6, 7, 8, 9. I want to know how many groups of three can be made where no ...
3
votes
0answers
89 views

Which mathematical game or puzzle did you invent?

A couple of weeks ago, a friend of mine showed me a extension of a game we are all familiar with that he was working on. The game we know is called Tic-Tac-Toe, and he was working on his own version ...
3
votes
0answers
67 views

Fisherman riddle: Combining probabilities

This is more a probabilities problem than a riddle. The riddle is: I am in a village, where a fisherman lives. The fisherman tells me that there is a 70% possibility that it will rain tomorrow. I ...
3
votes
0answers
60 views

Limits of infinite processes that terminate in finite time - checking my understanding?

I am a computer scientist by training, but have a fair amount of math background that I've picked up through classes, teaching, and general interest. A student of mine posed a question to me. I think ...
3
votes
0answers
83 views

The Fox And The Duck Puzzle

A duck, pursued by a fox, escapes to the center of a perfectly circular pond. The fox cannot swim, and the duck cannot take flight from the water. The fox is four times faster than the duck. Assuming ...
3
votes
0answers
73 views

Another machine problem

This is linked to my previous question Discounted optimization problem I have difficulties again finding a formula for $F(x)$. We consider a machine at time $t$ which is in state $x$. The machine ...
3
votes
0answers
58 views

Calculating that confidence that pairs of lightbulbs are independently illuminated.

So, you're sitting in a dark room, and on the far wall you see $n$ lightbulbs mounted above plaques numbered $1$ through $n$. There is a lightswitch on the arm of your chair. Every time you flip the ...
3
votes
0answers
124 views

Can this be only solved by trial and error?

The following question was asked in a competitive exam Rectangular tiles each of size 70 cm by 30 cm must be laid horizontally on a rectangular floor of size 110 cm by 130 cm, such that the ...
3
votes
0answers
76 views

Question, need help finding the source.

I was hoping someone could tell me if they knew the source to this problem: Let S be a subset of {1, 2, 3, 4,..., 10, 11}. We say that S is LUCKY if no two elements of S differ by 4 or 7. The ...
3
votes
0answers
100 views

Least characters in a numerical representation of integers

I was wondering what the shortest way to represent any given number is. For example, $387420489=9^9$. So, for this case, the smallest representation is of order 2 (2 numbers). Alternatively, ...
2
votes
0answers
64 views

Maximizing an algebraic expression using brackets

It's a riddle of sorts: given a list of numbers $\alpha_1 \dots \alpha_n$ and operators $o_1 \dots o_{n-1}$ which can be only $\times\, \mbox{or}\, + $ if the above is a specific algebraic expression ...
2
votes
0answers
75 views

placing coins on a table with a twist.

consider the classical puzzle, on a circular table, you and a friend take turns placing coins on the table and the first person who cannot do this loses. You can guarantee winning by placing the ...
2
votes
0answers
57 views

Minimum Overlap

You have a set of ten numbers, and you are trying to cover all 4-element subsets of this set. To do this, you choose 5 elements from the set every time and you cover all 4-element subsets of your ...
2
votes
0answers
109 views

Einstein's Riddle Alternative interpretation

I was working with Einstein's riddle yesterday and after some time I figured out a solution. But then I thought. What if the whole neighbourhood is a circle? (If you played GTA San Andreas like Grove ...
2
votes
0answers
134 views

Make one cube out of 8 little cubes

As part of a puzzle, you have to stack 8 little $1\times 1\times 1$-cubes so that they form one big $2\times 2\times 2$-cube. Now I want to check all possible solution to the puzzle and therefor I'm ...
2
votes
0answers
104 views

Can 24 lines on a cubic surface be realized as 24 identical spiral rods?

It's possible to put 24 lines on a cubic surface. 27 lines is possible, but I don't have a great picture for that surface. It turns out that the 24 lines can be built with Zome. I'm thinking that ...
2
votes
0answers
80 views

Is there a use for this technique?

I remember reading once about the following algorithm: Consider a lattice grid and $N$ houses situated at grid points, in which live the town elders. They want to choose a lattice point location ...
1
vote
0answers
33 views

Counting the number of cubes in an isometric view

I had seen questions in a sample aptitude test, where an isometric view of an object made up of cubes was given, with some of the cubes removed. We were supposed to count the number of cubes present ...
1
vote
0answers
56 views

Number of paths in a grid

A common puzzle problem is to count the number of paths that start from the bottom-left-hand corner of a grid and end at the top-right hand corner, with the restriction that you can only move upwards ...
1
vote
0answers
39 views

Math Puzzle, finding a sequence with a certain property

A certain number of the $5000$ members of the Conway Mathematical Society (each of which has a different membership number between $1$ and $5000$) got together to discuss a puzzle. Much to their ...
1
vote
0answers
33 views

Riddle about dog running in company of soliders

Group of soliders march togheter straight in square formation 50 x 50 meters. There is the dog at the back of the formation. Dog starts to run towards the first line of soliders and then when it ...
1
vote
0answers
71 views

Wedding Vows puzzle

My father came up with a puzzle and dared me to solve it. I could solve it by trial and error, but I rather want to solve it mathematically. It is the so called "Wedding Vows puzzle" where you have to ...
1
vote
0answers
46 views

When does a ball in a game of brick breaker never hit the remaining breaks?

I have a block size 2N*2N and some squares are filled with bricks and some aren't. I have a ball that travels distance 1 in the x and y direction and bounces off with perpendicular direction if it ...
1
vote
0answers
47 views

Finding the maximum number of voters satisfied in a ballot

Suppose you are given a file with the following information: 3W 4M 5 M2 W1 M3 W1 W2 M4 M1 W1 M4 W3 The top line specifies the number of candidates in each of two ...
1
vote
0answers
43 views

Visually apealing holologous transformation of a given contour

There is this problem which roughly says: You want to put a framed picture onto the wall with a cord to the picture frame. The cord is a single one, and both ends are attached to the frame. ...
1
vote
0answers
218 views

what is maximum number of points of intersection between the diagonals of a convex octgon?

What is the maximum number of points of intersection between the diagonals of a convex octagon (8-vertex planar polygon)? Note that a polygon is said to be convex if the line segment joining any two ...
1
vote
0answers
347 views

Cryptography puzzle

I'm currently broadening my knowledge in cryptography (or, at least, am trying to) and so I stumbled upon a puzzle I can't crack. It goes like this: You're given a set of pairs. The second number is ...
1
vote
0answers
498 views

Four candle problem: Using candles as timers

The candles each take one hour to burn completely. Cutting off bits of the candles is forbidden, but the candles are placed on a raft of fork handles so they may be burnt at both ends (e.g. to time ...
1
vote
0answers
72 views

What is the optimal investing solution for the given simulated market?

I have come across an artificial, simulated, stock-market type of situation, whose rules, I find, create a rather interesting problem. I want to know if there is a mathematically optimal solution for ...
0
votes
0answers
57 views

Optimized search for lock combinations

I came across an interesting puzzle the other day expressed as follows. You have a combination which has a dial on its face with the values of {1-30}. The combination that will open the lock is an ...
0
votes
0answers
81 views

uncleared Josephus problem equation?

I have been going through this problem and came across the simple solution as shown in Wikipedia. The formula for this solution is $$f(n,k)=((f(n-1,k)+k-1) \bmod n)+1$$ $$f(1,k)=1.$$ But due to ...
0
votes
0answers
14 views

Normalizing a Wait time To keep the Total amount of Time Used fairly Consistent

I need to perform a set number of operations in a unit of time. At the moment after each one I wait for a previously specified amount of time. After I have completed all operations I look at the ...
0
votes
0answers
86 views

puzzle creating questions

I am creating a game that player randomly draws 25 elements from 0-9 and 4 basic operations +-x/ from the sandbox .e.g. {0,1,4,4,5,5,5,+,-,*,/ ....... } , what require to do is based on that 25 ...
0
votes
0answers
175 views

Puzzle: Representing age using digits from birth-year in order. Impossible cases?

I recently wrote my friend a birthday card and thought it would be fun to write her age using mathematical operations on the digits of her birth-year in order. For example she turned 36 and was born ...
0
votes
0answers
55 views

What general function or rounding method can be derived from these number series?

OK, first of all, don't laugh, this is related to a social iOS game, but I promise there is some real juicy math here... I am attempting to derive a general formula or algorithm that can predict the ...