There are $10$ coins, one of which is a fake, and weighs either more or less than the others - you don't know which. There are two sets of scales - one tells the truth, the other lies (always says equal weighings are unequal, 50/50 with unequal weighings as to equal or wrong) - you don't know wh...

I'm not a sketch, but I can be drawn, I'm not origami, but I can be folded, I'm not a pill, but I can be swallowed, I'm not a haircut, but I can be short or long, I love fishing, dancing, playing, crafting, and fighting, What am I?

Demonstrating the Pythagorean Quadruple $6\times6 + 6\times6 + 7\times7 = 11\times11$ Using the pieces shown in the $11\times11$ square: The objective: Arrange the pink pieces (four enneominoes) into a $6\times6$ Arrange the blue pieces (six hexominoes) into a $6\times6$ Arrange the orange p...

This puzzle is part 3 of the Double feature series (first part here). The series will continue in "Double feature: Hot stuff". Rules of Ripple Effect1 Fill the grid so that each cell contains one number. The bold lines divide the grid into rooms. Every room contains consecut...

You see a boat filled with people. It has not sunk, but when you look again you don't see a single person on the boat. Why?

What is the minimum number of knights you need to place on a 10x10 chess board, such that every empty cell is attacked by at least one knight? Good luck!

Jack in all Tags... But Master in All? This puzzle is part of the "Piece de Resistance" series. Go back to Part 1 (Ace) for the story.Ace Two Three Four Five Six Seven Eight Nine Ten Queen King... Jack You finally flipped to your last card, and... a bunch of animals??? Tis' not Animal Farm, rig...

This is a three-dimensional Masyu puzzle. The five squares depict the layers of a $5\times5\times5$ cube. The goal is to make a single loop in 3D space which fulfills the following properties: The line passes through centres of cells and makes 90-degree turns only. The line can...

I own the value less than nine; Mother makes me if child get cry; Manager checks me to find which is high; Lose me, addicts might be about to die; I have various inside and outside; Who/What am I?

What is the minimum number of knights you need to place on a 9x9 chess board, such that every empty cell is attacked by at least one knight? Here is a similar question for a 10x10 chess board: Knights covering a 10x10 chess board Hint: Good luck!

$0,4,8,21,52,65,96$ Given this set of numbers figure out the pattern they follow and write down the next seven numbers in the sequence. Hint:

Related to this Q&A. I am looking for a pattern that could be applied in order to solve this Sudoku. The current patterns that I apply: Ensure that every digit appears once in every block Ensure that there is a unique sequence from 1 to 9. Now I am blocked as the block top right could cont...

My first, a sight to behold before a drink My second, in the drink My third, a place for a drink My last, what may arise among lads after some drinks What am I?

This puzzle is part of the ‘Twelve Labours’ series. Previous instalments can be found here: Prologue | 01 His first labour now complete, Hercules made his way up the street to the storage depot for Lernaean Hydration, a wholesaler of alcoholic drinks. The owner, Minos, met him on the thresho...

A riddle my math teacher asked back in 10th grade: I am a fruit. If you take away the first letter of my name I become a crime. Take away the first two letters of my name I become an animal. Take away the first and last letter of my name and I become a form of music. What am I?