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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1
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2answers
353 views

puzzle 3-d visualization

729 small cube are painted pink on each face and then arranged to form 27 identical middle-size cubes.Each middle size cube is painted black and then arranged together to form one large cube. And ...
-1
votes
1answer
31 views

Some kind of encrypted message in a computer game [on hold]

I'm not sure whether this is a place where I can ask this, but if anyone can help me please do so. I play an MMORPG game where many races have different histories in their books that players can ...
1
vote
1answer
34 views

Can I find the frog jumping on leaves? 2 “contradictory” answers

I've encountered this question and found two "contradictory" answers to it. of course they are not really contradictory, but I'm having some trouble explaining why not. Say there is a frog standing ...
3
votes
1answer
44 views

find a group of lowest N numbers so that no 2 pairs have the same bitwise or

I am trying to find the lowest group of N numbers (i.e. N=1000) so that no 2 pairs from the group have the same bit-wise or. more specific need to find a group $A = \{a_1,a_2,a_3,..,a_N\} $ such ...
-5
votes
0answers
39 views

Puzzle, can anyone help solving this? [closed]

Could anyone solve this? been thinking about it all day and starting to feel stupid. Q12 and Q16 on http://www.arealme.com/iq-2015/en/
5
votes
0answers
94 views

Puzzle - In how many pairings can 25 married couples dance when exactly 7 men dance with their own wives?

Each married couple as well as each dancing pair consists of a man and a woman. How many possible pairings are there? Here is the same question with a different amount of couples. I read the answers ...
1
vote
0answers
35 views

A harder long division puzzle than the first; what should “Algebra I” solution look like?

Here's another problem, significantly harder than the first, but still accessible to target audience. The statement of the problem (i.e., northwest corner only) comes from a PennyDell puzzle magazine: ...
4
votes
0answers
69 views
+50

Cover the grid graph with simple cycles

I have a two dimensional n x m grid graph. And I want to find in how many ways this grid can be covered with simple cycles (it can be a one cycle or it can be many ...
6
votes
3answers
87 views

“Long-division puzzles” can help middle-grade-level students become actual problem solvers, but what should solution look like?

This is my first post. I hope it's acceptable. EDIT Since there are people to whom such notation is foreign, I will point out that the problem represents KRRAEE / KMS, where PEI is the quotient and ...
2
votes
1answer
56 views

P. Winkler's puzzle “Inscribing a Lake in a Square”

This is a puzzle from P. Winkler: "Show that, given any closed curve in the plane, there is a square containing the curve, all four sides of which touch the curve." I was NOT able to solve it quickly ...
1
vote
2answers
85 views

Three knights on a 3x3 chess board

There are two white knights (W) and black nights(B) positioned at a 3x3 chess board. Find them minimum number of moves required to replace the black knights with the whites.Any type of move is ...
4
votes
2answers
111 views

Maths Puzzle: Partitioning a set into two disjoint sets

Le $X$ be the set of all non-empty subsets of $\{a,b,c,d,e,f\}$. So $X=\{a,b,c,d,e,f,ab,ac,ad,ae,af,bc,bd,be,bf,cd,ce,cf,de,df,ef,abc,\cdots,abcdef\}$; i.e., $|X|=63$. We want to partition $X$ into ...
2
votes
1answer
56 views

The Sieve of Alice- Number theory Riddle

I am trying to prove the result for a problem which I am unable to do so! The answer is simply $\frac{N}{2}$ when N is even and $\frac{N}{2}+1$ when $N$ is odd. But I do not see why?? Can you give me ...
2
votes
1answer
83 views

Is there an equation that can lead to the correct pattern for the answer to this riddle?

Here's a riddle I came across recently: There’s a group of six friends who are all musicians. One day, they decide to have a few performances between themselves so that they can hear each ...
3
votes
3answers
1k views

Place maximum Rooks on a chessboard

I am given a chessboard of size $8*8$. In this chessboard there are two holes at positions $(X1,Y1)$ and $(X2,Y2)$. Now I need to find the maximum number of rooks that can be placed on this chessboard ...
2
votes
2answers
71 views

Simple Puzzle: A Matter Of Time

I am trying to solve a simple puzzle: Fifty Minutes ago if it was four times as many minutes past three O'clock, how many minutes is it to six O'clock. I tried solving it: Let x be the minutes past ...
2
votes
0answers
44 views

Why 6 races is not sufficient in the 25 horses, 5 tracks problem

The horse-racing puzzle has been asked on mathSE several times (1, 2, 3, 4); there is also a generalization. I restate the puzzle below: 25 horses all run at different speeds. You can race 5 ...
0
votes
1answer
69 views

How should one go about deciphering “ZPLKKWL MFUPP UFL XA EUXMFLP”? [closed]

The Princeton companion to mathematics says, "it is just possible to work out the meaning of the above example by matching letter patterns to those commonly seen in English, but it is quite ...
0
votes
1answer
37 views

Maximum number of teams of three people such that each team is built in one of two ways

A coach picks team members in two ways:   A. The team of three people should consist of one experienced participant and two newbies. Thus, each experienced participant can share the ...
22
votes
3answers
5k views

Why does this age calculation trick work?

The trick works like this: Take the current date in the format yyyymmdd and subtract it with your date of birth taken in the same format. Drop the last four digits to get your age. For example, I was ...
0
votes
1answer
81 views

A puzzle about choosing one of 9 doors with signs on them

This problem involves logic-based math, I tried making truth tables for this problem but I don't think you can because there are 9 doors! Below is what I came up with but I want to know if there is a ...
3
votes
1answer
36 views

Diophantus' Lifespan

Today I saw Diophantus' Epitaph. For those of you who don't know it and don't feel like googling: 'Here lies Diophantus,' the wonder behold. Through art algebraic, the stone tells how old: 'God ...
10
votes
0answers
198 views

Finding real money on an even stranger weighing device

You have $n$ coins which each weigh either $20$ grams or $10$ grams. Each is labelled from $0$ to $n-1$ so you can tell the coins apart. You have one weighing device as well. At the first turn you ...
-1
votes
1answer
51 views

Krypto analysis

The game Krypto is where you get 5 numbered cards dealt with you by the dealer and then a sixth card that you must connect the five cards to with mathematical symbols. The values of the first 5 cards ...
-2
votes
1answer
244 views

Nice combinatorics puzzle [closed]

INTRODUCTION Around 1980 my father told my a simple yet interesting mathematics puzzle. It was similar to the "two professors puzzle". I don't remember all the details, but it had three "I don't ...
2
votes
0answers
20 views

Symbolically formulate the two guard problem so it can be solved by a computer

Take the classic two guard riddle (I don't know where the origin of this riddle is, so I'll take the version from http://www.calpoly.edu/~mcarlton/riddles.html): You stand at a fork in the road. ...
3
votes
1answer
64 views

Frazzle game question

In $7^{th}$ grade, in order to learn divisibility, memory, and focus, my math teacher had my pre-algebra class play a game called Frazzle. To play the game Frazzle, each person went around the room ...
1
vote
0answers
115 views

Balancing the weights of the vertices of a graph by averaging along the edges.

Suppose that you have a graph, and someone assigned real numbers to every vertex. You can modify these numbers by replacing the numbers on two adjacent vertices by their average. Your goal is to reach ...
-3
votes
2answers
43 views

Find the missing dollar [duplicate]

Three friends eat at a restaurant and finally ask for the bill. They pay the 75 dollars by dividing it equally (so they spend 25 dollars per person.) The waiter takes the money to the owner, who, in ...
0
votes
0answers
63 views

Is there a general solution to the water-bucket logic problem?

Having an infinite supply of water and two containers, one for 3 liters and one for 5 liters, how would you measure 4 liters? Each step in the solution can be one of three things: Fill up a container ...
2
votes
1answer
42 views

Puzzle: Determining the structure of a bipartite graph

Consider the bipartite graph $G = (X, Y, E)$, with $|X| = |Y| = n$. We can think of $X$ and $Y$ as clusters of $n$ switches on either end of a long hallway. Each switch on one end of the hallway has ...
2
votes
1answer
86 views

A math puzzle about slow clock

You have the misfortune to own an unreliable clock. This one loses exactly 20 minutes every hour. It is now showing 4:00am and you know that is was correct at midnight, when you set it. The clock ...
2
votes
1answer
31 views

Derive a formula for the number of small square base pyramids required to create a bigger pyramid?

To quote from the problem statement: "Pyramids are built using smallest pyramids of "level 1", that are used as building blocks for higher levels. Stacking pyramids of "level 1" to create ...
12
votes
2answers
368 views

Sum numbers game

$2n-1$ numbers are lined up as follows: $n$ , $n-1$ , $n-2$ , $\cdots$ , $2$ , $1$ , $2$ , $3$ , $\cdots$ , $n-1$ , $n$ At each step, one can choose any number in the line and add it to each of ...
21
votes
4answers
719 views

Finding real money on a strange weighing device

You have 50 coins which each weigh either 20 grams or 10 grams. Each is labelled from 0 to 49 so you can tell the coins apart. You have one weighing device as well. At the first turn you can put as ...
0
votes
1answer
79 views

Can this expression be made true ? 2 _ _ _ _ = 2015

Make this expression true: 2 _ _ _ _= 2015 The underscores must be replaced by any 2 of of the operational symbols +, - , x, / (divide). And any 2 of the digits 0,1,2..9. So, you basically need 2 ...
2
votes
2answers
80 views

Probablity of $k$ balls go into at most (including) $m$ boxes, with $n$ given boxes ($m\le n\le k$)

Suppose I have $n$ boxes, and an infinity of balls. All balls are regarded the same. I randomly throw balls into the boxes, each time the ball may be thrown into one of the box, with equal ...
0
votes
0answers
12 views

Given An initial point and final point ,How to determine the number of Co-Ordinates(x,y) such that both x and y are integral?

I have thought a lot about it and still no clue. I thought of visualising the initial point and the end point in the form of a Grid. But ,soon I was over with my resources. Problem: Given an initial ...
0
votes
0answers
30 views

Right answer probability [duplicate]

I thought I'm familiar with probability, but this question got me a little stuck: If one choose an answer to this question completely random, the probability of choosing the right one is: A) ...
3
votes
1answer
102 views

Is my answer correct? Expected number of coin flips to get 5 consecutive heads

I found this puzzle online. Before my question gets flagged or on hold, I know the question has already been answered here but since I tried to solve it on my own I want to check if it's correct or ...
1
vote
1answer
62 views

Is there a mathematical way to determine a solution for puzzle games?

Or more specifically, a mathematical way to determine HOW to solve a puzzle game. Take a look at this screenshot of a puzzle game "The Talos Principle." As you can see, the purpose of this ...
3
votes
2answers
545 views

The sum of digits of $3(3x+3)$ is always $9$ for any $x$ between $1$ and $9$

Given the following 'joke' I stumbled across today It's easy enough to figure out that the answer is always 9. Asshole. However when I tried to 'prove' this for ...
5
votes
3answers
101 views

Number of ways through a modified grid

I was in math class listening to my teacher blather on about solids of revolution when my friend passed me a note with a puzzle on it. It looked something like this: How many different ways can you ...
0
votes
2answers
33 views

Aptitude: Time and Work

6 men can complete a piece of work in 12 days. 8 women can complete the same piece of work in 18 days, whereas 18 children can complete the piece of work in 10 days. 4 men, 12 women and 20 children ...
5
votes
2answers
136 views

A Knight and Knave Problem

There are $69$ people in a room, of which $42$ are truth-tellers (they always tell the truth) and the rest are liars (they can lie or tell the truth). You are allowed to ask any person $A$ whether ...
0
votes
1answer
37 views

Reasoning - Seating Arrangement

Eight fiends P, Q, R, S, T, V, W and Y are sitting around a square table in such a way that four of them sit at four corners of the square while the rest sit in the middle of each of the four sides. ...
5
votes
2answers
111 views

How to solve this riddle?

How to solve this riddle? All rooms have the same shape and size. Every room has one entrance, and two exits: one on the left, and one on the right (on opposite directions). Both exits lead to a ...
0
votes
0answers
25 views

How many closed knight's tour are possible in a $8\times 8$ chessboard? [duplicate]

How many closed knight's tour are possible in a $8\times 8$ chessboard? I hae no such idea. Please give me the proof of it.
3
votes
1answer
132 views

Optimal strategy for 2 players Lights Out game variation

Consider a turn-based game for 2 players. They're both playing on the same board. The board is 8x8, randomly generated and each cell has 0 or 1 (with equal probabilities), for example: ...
3
votes
1answer
67 views

on which floor does she lives?

A woman lives in a 36 floor building. There is a lift in that building. When she leaves her aprtment and goes to lift,there are 3 times chances lift will take her up than take her ...