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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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Logic Puzzle Question

Suppose there is a vending machine that sells Coke and Sprite. This particular vending machine has 3 dispensers, one for Coke, one for Sprite, and the last one either dispenses Coke or Sprite at random. There's just 1 problem, all of the labels for…
user750949
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Solving logical matrix

Can anyone explain why the selected option in the attached image is the correct one? (Need it for uni entrance test) Logical Matrix
Mark Fooster
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Filling numbers in 19 cells set in a big hexagon such that....

In social groups this question (see the photo below) of filling integers in 19 small cells set in a big hexagon is asked, such that their sum in each layer(row) in all three directions is 50. Next, it asks one to find the sum of numbers in 7 pink…
Z Ahmed
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Will you find a way to quickly find out if this number has a $0$ in the tens digit?

Here's how the puzzle works! Here is a list of numbers : $1,2,3,4,5,6,7,8,9$ I will give you some numbers in this list (numbers can be repeated). When receiving those numbers, you will multiply them and then find if the tens digit has a $0$. You…
Jotadiolyne Dicci
  • 374
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1 answer

What number should be placed in that last slot?

I came across a very difficult puzzle. What number should be placed in that last slot? I only know 16 is not the correct answer, because 11 is before 10.
James
  • 1
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1 answer

First level 4-digit numbers (Kaprekar connection)

Suppose $A>B>C>D$ be four unit digit natural number and $P_1=ABCD$(descending digits) and $Q_1=DCBA$ (ascending digits) and $R_1=P_1-Q_1$, according to Kaprekar $R_1$ could be 6174. If not then go to the second level by constructing $P_2$ and $Q_2$…
Z Ahmed
  • 43,235
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6 answers

A rectangle inside a circular sector of an acute angle

In the math puzzle book by Gardner, the maximum area ${\cal A}$ of the rectangle inscribed in the sector of unit-radius circle (see the Fig.) with angle $0 < \theta \le \pi/2$ has been asked to show as $${\cal A }=\frac{1-\cos \theta}{2\sin…
Z Ahmed
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An interesting feature of $857142$

In 2002, a math competition of India named Pradanya meant to ask two 6-digit numbers $P=abcdef$ and $Q=defabc$ such that $P=6 Q$. We can write $P=1000X+Y, Q=1000Y+X$, where $X=abc$ and $Y=def$ are 3-digit numbers. Then we get…
Z Ahmed
  • 43,235
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1 answer

Would the man in the white room have a 100% of crossing the line?

I had this thought in my head for a couple of months now and I really wanted to see what the answer to it is. So here it is: A man is sitting in a white room, where all he has to do is cross over a purple line to travel back to Earth. However, he…
Display Name
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2 answers

Faulty machine problem variation

I don't know if this problem is known by any other name. The classic problem is: We have 10 machines that produce balls, each weighing 10grams. One of the machines, however, produces balls weighing 9 gramms only. We are allowed only one weighing and…
Nik
  • 793
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0 answers

Jigsaw puzzle in which each piece has 3 tab and 1 blank. How to check if given number of rows and columns, the puzzle is solvable or not?

You are given a special jigsaw puzzle consisting of n⋅m identical pieces. Every piece has three tabs and one blank, as pictured below. The jigsaw puzzle is considered solved if the following conditions hold: 1. The pieces are arranged into a grid…
vedant bharti
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How to find the answer of this puzzle: $17 \times 4 = 68 + 25 = 93$?

Answer: 17 x 4 = 68 + 25 = 93 I have asked the guy who got the answer right in this Reddit thread, but hadn’t get reply from him. Do we use trial and error?
Casablanca Kookie
  • 11
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Probability of solved taxicab number upper bounds

I was reading about taxicab numbers on Wikipedia at: https://en.wikipedia.org/wiki/Taxicab_number#Upper_bounds_for_taxicab_numbers What is the probability that these upper-bound values above Ta(6) might be the actual solutions?
user349633
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3 answers

Island with liars and truth tellers (logic)

We had a question about an island full of truth tellers and liars. There were a lot of questions, however there was one I couldn't wrap my head around. It went as follows: A random islander approaches you and says the following 2 declarations: I…
Silver
  • 3
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1 answer

In a $n \times n$ board there are total $n^2$ bulbs. If one touches any bulb the bulbs in that row and column is off.

At first all bulbs were on. At each touch the state of bulbs in that row and column is changed. If it is off the after touch it is on and if it is on then after touch it is on. Find the minimum number of touches to off all the bulbs? I am able to…
user690488
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