Mathematics Stack Exchange
Mathematics Stack Exchange

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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How to approximate 1/3 by only add/subtracting powers of 2

How approximate $\frac{1}{3}$ up to four significant digits by using only $\pm2^n$ where $n$ is a negative integer. Preliminary attempt/example: $$0.33\approx0.25+0.0625=0.3125$$ $$=2^{-2}+2^{-4}$$
Luna
  • 201
2
votes
1 answer

Minimising the maximum number required for problem

You are in charge of giving land to different numbers of individuals and below is how you have divided the land into 10 areas. You can assign any number of people from 1 to $n$ to live in each area under these conditions, that no neighbouring areas…
Ben Franks
  • 423
2
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2 answers

Where is $1 gone!

Possible Duplicate: Riddle (simple arithmetic problem/illusion) Three men go to a shop and take some food which is cost $25. Waiter came and gave them bill. 
Each of them gave $10. So, waiter take total $10+$10+$10=$30. Waiter came back with…
enam
  • 259
2
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1 answer

Help with a riddle

I'm having a discussion about the following riddle with a friend. There is a boy behind each girl, and a girl behind each boy. What is the smallest number of children required to do this? I say the answer is 0, they say 2 (if they stand back to…
Tim Trewartha
  • 123
2
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2 answers

Can the overall percentage override the individual ones?

Suppose I have 2 white bags A and B, and 2 black bags C and D. All these bags only contain a bunch of cool beans and bad beans. Bag A has a greater % of cool beans than C. Bag B has a greater % of cool beans than D. I combine the two white bags into…
Minden Petrofsky
  • 323
2
votes
1 answer

Ebert's Hat puzzle with [7,4] hamming code

I've been researching Ebert's hat puzzle and I keep reading that the 7 person case can be optimized using the [7,4] Hamming code. Can someone explain to me how the players could use Hamming codes to maximize their chances of winning?
1233211
  • 797
2
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2 answers

Sliding puzzle disjoint sets proof

Prove that the states of the 8-puzzle are divided into two disjoint sets such that any state in one of the sets is reachable from any other state in that set, but not from any state in the other set. To do so, you can use the following fact:…
user41500
  • 23
2
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1 answer

How do you convert this diagram into a linear system of equations/matrix form?

Question: Given is the following pipe system: the pressure in a stationary state is at every end and cross-point (with exception of $K_i, i =\{1,...,4\}$) equal to the average pressure of the neighboring points. On $K_i$ with $i = \{1,...,4\}$ are…
ghshtalt
  • 2,753
2
votes
2 answers

Impossible problem? -- Bisecting and combining stacks of coins

I encounter this problem about dividing and combining stacks of coins. Now, the problem uses coins because it's easier to visualize, but it need not to be, it is in fact misleading because real coins can't be infinitely subdivided. So, for the…
Luna
  • 201
2
votes
1 answer

Number of ways of getting from a certain point to another point.

Calculate the number of ways of getting to the pizza without stepping on bombs (you can move up and right) My solution was to calculate the number of ways of getting from the snail to the pizza (without the including the bombs) and subtracting from…
Mike B.
  • 110
2
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1 answer

Puzzle: Each entry in a number grid is the average of its neighbors

I'm trying to solve the following puzzle: Each number should be the average of its four neighbors. For example, $x$ should be equal to $\frac{1}{4}(4+10+y+z)$. I don't know how to make a formula out of it. What's the trick? Can anyone give me a…
Ket
  • 21
2
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2 answers

Math riddle: reach sum of 100 with numbers $0...9$

This is a riddle my friend gave me and we don't know the answer so we would like some help. The task is to use all of the numbers $0,1,2,...,9$ once each to get a sum of $100$ only using the plus sign. You can do whatever you want with the numbers…
Themistoklis Haris
  • 239
2
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3 answers

Coin Arrangement Puzzle

Disclaimer: I'm not sure how math related this puzzle is (it could potentially be), but I thought it was an interesting puzzle, and I also don't know how to solve it so I wanted to see if anyone had any ideas. You have a board divided in quarters…
Matt
  • 2,979
2
votes
2 answers

Next term in the pattern

$22+22=4444$ $43+46=618191$ $77+77=?$ What should come in place of $?$ I cannot see any logic in $43+46=618191$. Is there any?
Mathematics
  • 3,973
2
votes
2 answers

What is the fair price of the game below?

You are playing a fair die game with 'n' die rolls. You have decided on the "fair" price of the game. So, to take part in this game you need to pay upfront this value. Then you get to roll a die, n times. If you ever role a die more than or equal to…
user300817
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