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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.

Many puzzles, games, and riddles are based on mathematical concepts. This tag is for questions that ask about the mathematics behind a puzzle, game, or riddle, or about the solutions to mathematical puzzles.

If you already know the answer to the puzzle you are posting, you might consider posting your question on Puzzling Stack Exchange, instead. If you do end up posting your question on Mathematics Stack Exchange (MSE), please read the following meta posts on these kinds of questions before asking your question:

If you do end up posting on MSE, please make it clear in your question that you are "puzzling" the community and that you will be answer the question yourself if no one in the community posts your desired solution.

3301 questions
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the time at which the hour & minute hands in a clock becomes straight?

At what time exactly does the minute hand and the hour hand in a clock becomes straight between 7O'clock & 8O'clock. Iam getting the time is in between 7:05 and 7:10 but what after that. can it be solved using graph theory ?
Suraj M S
  • 1,891
3
votes
2 answers

A $5\times 5$ square with $+1$ and $-1$

This is a problem from the Monthly Contest of the Berkeley Math Circle in 2001/2002. The Problem A 5 ×5 square has been dissected into a unit square grid. One of the unit squares has been filled with “−1” and the rest have been filled with “+1”. In…
Tito Eliatron
  • 6,612
3
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1 answer

The maximum product of two numbers which together contain all non-zero digits exactly once

I found the following puzzle: Use all the digits from 1 to 9 without repeating, to form two numbers such that their product is maximum. A digit used should be unique across both the numbers. For example, the numbers formed could be 1234 and…
user70810
  • 31
3
votes
1 answer

Identifying traitors

Logic is one of the facets of math that is more 'fun', but this one is beyond me. Consider using logic statements and/or truth tables. 'Or' here is inclusive, that is 'A or B' means 'A or B or both, but not neither'. King Warren suspects the Earls…
Y-dog
  • 627
3
votes
0 answers

Puzzle to trap cat by blocking points

Consider usual $3$-dimensional space with integer points $\{(x,y,z)|x,y,z\in \mathbb{Z}\}$. The player is trying to trap the cat at the origin. The player can block one point. The cat can move to either direction of $(±1,0,0), (0,±1,0), (0,0,±1)$,…
aerile
  • 1,437
3
votes
2 answers

Place any number of parentheses into $1\div2\div3\div4\div5\div6\div7\div8\div9\div10$ to get the number $256/63$

Place any number of parentheses into this expression to get the number $256/63$ $$1\div2\div3\div4\div5\div6\div7\div8\div9\div10$$ I was able to get $63/256$, but I don't know how I would get the reciprocal.
user842445
3
votes
2 answers

Find the odd ball out out of $18$ balls, where $17$ weigh the same.

There are many variants of this problem. The one I am working with is There are $17$ balls that weigh the same, and $1$ ball that could weigh either heavier or lighter than the other $17$. How many weighs on a balancing scale do you need to…
24n8
  • 1,455
3
votes
2 answers

Apples Across a Bridge (word problem)

Here is a fun problem that I am having trouble answering: Let’s say I live in Town A, and I want to transport 249 apples across a bridge to Town B, but I can only carry 100 at a time. The bridge is 100 feet long, and I will lose one apple every foot…
Jaken
  • 31
3
votes
2 answers

Cats on a cliff puzzle

On a cliff of length 110m at a height 240m, 10 cats are positioned facing either the left or right direction arbitrarily. The length of the cliff is large compared to the size of each cat. Initially, all cats start running in the direction they are…
winkingPanda
  • 39
3
votes
3 answers

Puzzle Remaining Numbers on board. Erase 2 numbers but add the difference

This is the question I get from Geeks For Geeks. The problem is, given the first $50$ natural numbers, i.e., from $1$ to $50$ which are written on a board. Select two of the numbers on the board, say $a$ and $b$, write the absolute value of their…
Sprint
  • 31
3
votes
1 answer

n-bucket water puzzle

Inspired by this post. I am thinking of a general case. Reference to read. Suppose $N,L_1,L_2,p,q$ are integers, and $N L_1 = pq$. with $p\ge 2$ and $L_1>L_2$. Now you have $N+1$ buckets, the first $N$ buckets are full of water, each of these…
Yimin
  • 3,311
  • 17
  • 32
3
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1 answer

A Particular Peg-jumping puzzle

Many years ago I was shown this puzzle. It's a type of solitaire or peg-jumping puzzle. One places some arbitrary arrangement of pieces on a rectangular grid, below the grid dividing line (the bar). Then you perform a sequence of jumps. A jump is…
Jim White
  • 616
3
votes
0 answers

Puzzle: You have 9 weights. How can you determine which two groups of four weights are equal in the least steps?

You have 9 weights, but you don't know how heavy they are. You also have a balance scale, which you can use to compare any two groups of weights. For example, you could compare the first two weights with the next three, and it would tell you whether…
Taylor
  • 31
3
votes
2 answers

Divide $40$ to $4$ parts such that every number from $1-40$ can be realized

How can you divide $40$ to $4$ parts such that every number from $1-40$ can be realized just by adding or subtracting those $4$ parts?
GajendraSinghParihar
  • 133
3
votes
4 answers

Numerical puzzle

I'm stuck here with some numerical rebus - Given: $A^2=BC, A^3=CA$ Find: $A+B+C$ $13$ $12$ $11$ $10$ (only one correct solution) Note that letters represent digits. I can't think of any idea to solve this one, and according to the book from which…
artyh
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