The unexpected hanging is described in the Wikipedia article Unexpected hanging paradox. A hanging is said to be a surprise of on the morning that the prisoner is hanged, he cannot deduce that he will be hanged that day. I don't see the ability to derive a contradiction. If you assume that the j...

This puzzle is part 23 of Gladys' journey across the globe. Each part can be solved independently. Nevertheless, if you are new to the series, feel free to start at the beginning: Introducing Gladys. Dear Puzzling, You'd think that after so many days on the road I couldn't...

Given the shape below, the challenge is to bisect it by placing the two segments on the shape. The resulting two shapes need to have the same area but does not need to be the same.

This is an extension of What is the strategy to solve Simon Tatham's Twiddle? in that it explicitly goes beyond the default gamemodes of Twiddle The Number Rotation Puzzle (NRP) is a combination puzzle in which the goal is to rearrange a scrambled rectangular grid of numbers back into order vi...

We are given countably many people numbered $1,2,3,\ldots$ for all $n\in \mathbb{N}$, each wearing a hat that is either black or white. No-one can see the color of their hat, but everyone can see everyone else's hat. Now everyone has to guess the color of their hat. Give a strategy that guarant...

I originally saw this on r/puzzles, and thought it deserved a place here. I have a solution to this puzzle, but it's really long and ugly. If anyone comes up with something simple, please share! Two perfect logicians have the following conversation. Fill in the blank with the correct number...

This puzzle is part 24 of Gladys' journey across the globe. Each part can be solved independently. Nevertheless, if you are new to the series, feel free to start at the beginning: Introducing Gladys. Dear Puzzling, By the time you receive this message, I may have already r...

$Extend$ $this $ forever $series $ $by $$five $ $more$ $terms:$ 17, 3, 5, 7, 11, 17, 2, 3, 5, 11, 13, 17, 2, 5, 7, 11, 13, 2

A friend of mine sent me this puzzle, to solve it you need to use: 1) basic arithmetic operations. 2) Multiple numeral systems.

While attacking a recent puzzle (whose solution ended up being entirely different from what I was trying), I was inspired to create a number-sequence puzzle with a sequence $(p_n)$ of primes where the secret rule is $p_{n+1}$ is defined as the lowest prime factor of the number $2^{p_n}+1$. ...

I have thought of a 6 letter word: but I'm not going to tell you what it is. Instead you give me 6 letter words, and I mark them according to the normal rules of Mastermind. A 'word' can be garbage if you want, e.g. PZQABC, or a normal word like BUTTER. These get marked as 0r1w and 0r2w respe...

Your brothers have taken over your bedroom for over a week! However, you know you're powerless to move them unless you can solve their quest: "Bring the tool that best describes this room." You head to the garage to pick your weapon of choice, but which one do you pick and why?

Inspired by this puzzle, I decided to make my own guess-my-character puzzle. The only different thing is that mine isn't based on images. This is the first time I'm making a puzzle, so here's my try: 1 – I start with: I am not a girl. I'm not considered intelligent. I don't like cake. I don't...

Michelle has a deck of 52 playing cards, stacked in a pile with their backs facing up. She takes the first 2 cards in the pile, turns them over, and places them at the bottom of the pile. She now takes the next 3 cards in the pile and, once again, turns them over, and places them at the bottom of...

Standard 9x9 Sudoku utilizes digits 1 to 9. You are only allowed two distinct Primes to represent 1 to 9. Find out the minimum number of characters (digits+signs) needed to construct Sudoku Puzzle with unique Solution. Allowed Signs are... +,-,/,X,!.

Okay, so this is based off of https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/pattern.html And, my cousin made a random pattern and gave it for me to solve. Unfortunately, the logic is beyond me. So i'll give it to for you guys to solve! Rules You have grid of squares, and you have...

Comedian's hollow lies 'bout the bottom of the lake: "The head of the snake with a ring in day's break". (3 6) Who are we describing?

Warning: If the wording seems cryptic to you, that’s because it is meant to be. Here’s a puzzle for you: legally place the black king in the following diagram. Additionally, assuming that all white pawns were passed and black’s pawn structure was set up by the game’s 18th move’s end, what wer...

I seem to be getting more forgetful these days. Today I can't remember my password to my super-secret Puzzling sock-puppet account. I know I did that thing where you use the first letters of words of some phrase or whatever. And I left myself a "password hint" - it follows the pattern Xxxx:xxxx.X...