Top new questions this week:
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During a recent thorough cleanup round at the main building of the San Fransisco Chronicle, an employee found a piece of paper stuck behind an archive closet in one of the many archive rooms.
Her ...
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This problem was given to high school students by the Russian prime minister Mishustin.
We have a circle. We are given some point on the circle and its diameter, as shown below. We are given a ...
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What number should replace the question mark? Explain why.
...
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Let $k < n$, $k$ even, $n$ odd. Mary is to play $n$ chess games against her parents, alternating between her father and mother. To receive her allowance she must win $k$ games in a row. Given the ...
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Which person's photograph should be pasted upright (NOT UPSIDE DOWN) in the blank space?
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Can you fill in the circles with numbers such that:
Each pair of circles connected by one line contains relatively prime numbers
Each pair of circles connected by two lines do not contain relatively ...
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This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
Resolve the ...
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Greatest hits from previous weeks:
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I believe in a number of books I have read and solved myself, the introduction stated that guessing should never be necessary for any of the puzzles in the book. Instead, a handful of techniques ...
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You are a prisoner in a room with 2 doors and 2 guards. One of the doors will guide you to freedom and behind the other is a hangman–you don't know which is which, but the guards do know.
One of the ...
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After every time you guess, you're told if you're right, too high, or too low. Is there a strategy you can use to guarantee you'll get it on your 6th attempt (or lower)?
I know a strategy to get it ...
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What is the complete set of 10-digit numbers using each value ($0$-$9$) once, such that the first $n$ digits form a number divisible by $n$ (for $n \in \{1,2,...,10\}$)?
E.g. if the number were $...
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I am a seven letter word. If you remove one letter from me my meaning does not change. If you remove two letters from me my meaning still does not change, and if you remove three letters from me, my ...
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Looking for an intuitive solution to the following problem:
In a certain country the following coins are in circulation: 1 cent, 2 cents, 5 cents, 10 cents, 20 cents, 50 cents, and 1 dollar. It is ...
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Without using a calculator or a computer can you determine which of these two numbers is bigger: $2$ or $1.005^{200}$ ?
I saw this puzzle in a YouTube video, which I will post later.
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Can you answer these questions?
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This puzzle is part of the Monthly Topic Challenge #16: Restricted Title: xkcd 2000-2500.
Solve the following 10 sub-puzzles, then use the information you've found to solve the metapuzzle:
Puzzle 1
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I just joined Puzzling Stack Exchange, and the moderators decided to put me through a test to validate my account. They brought me to an unknown island, where lies nothing but a maze:
I managed to ...
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A team of archaeologists has discovered an ancient clay tablet. They understand the script it is written in, and have transliterated it to the Latin alphabet, but they do not understand the language. ...
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