# Questions tagged [logical-deduction]

A puzzle that requires formal logical deduction to arrive at the solution. This suggests more than merely reasoning through clues to find an answer (you might want [situation] for that).

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2answers
255 views

### Cover 63 squares of a chess board

Can you find 3 similar geometrical figures (common shape but can be different sizes) A, B and C with the following property: If you remove any square from a 8x8 chess board, then the remaining area ...
1answer
527 views

### Three shy fairies performing two thousand times

Three shy fairies participate in a dance competition. Since they are shy they don't want to be seen by anyone except for the five judges of the competition. The competition is composed of $2000$ ...
1answer
530 views

### One piece of a destroyed chess board

Once I met a friend and he told me the following story: I recently cut my wooden 8x8 chess board into different rectangular pieces along the edges. Each square of the chess board has a length of one ...
1answer
184 views

### Circular arrangement with professions and age based puzzle [closed]

Eight people, named A, B, C, D, E, F, G, and H; who work as a dancer, singer, lawyer, painter, doctor, teacher, architect, and professor; are 25, 40, 45, 29, 66, 24, 21, and 34 years old; although ...
1answer
1k views

### This new puzzle type needs a name {3}

I believe I have invented** a new type of puzzle... What is its name? ** Well, 'adapted' an existing one, really... Colour-blind-friendly version available here. Those without colour-blindness ...
2answers
459 views

### Pensive Nonogram - Two-Colour Puzzle

Fourth two-colour puzzle in the 32nd issue of Mega Pixel Puzzles by Puzzler.. I’ve made some progress, but I am stuck. Can you help me find my next move in it? (The puzzle is below)
4answers
2k views

### Four buttons on a table

I was asked lately (in an interview) to solve this puzzle, which is similar to the 4 cups on table puzzle. In a certain room there is a rotating round table, with 4 symmetrically located ...
2answers
490 views

### Compoundoku wants BIG

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) ...
2answers
262 views

### Can you open a safe with a lengthy complicated combination?

Two cousins were talking about their parents' safes. "They said I can keep my comic books in their safe, if I figure out the right combination, and enter it on the keypad correctly on my first ...
4answers
216 views

### Which figure is not needed in the pattern?

I have been trying to figure it out, but no logic so far. This question was given to me by the University of Sofia.
1answer
256 views

### wandering knight

Suppose a land with a finite number of castles. Each castle is connected (via roads) with exactly 3 other castles. One knight leaves from his castle and starts travelling. He moves in the following ...
2answers
1k views

### Introducing: Compoundoku!

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) ...
2answers
105 views

### How to effectively hide an earth rebooter thingy [The Good Place Season 4 spoilers]

This puzzle is unsolved. I don't know if there is a solution or how to solve it. I'm also not sure what type of puzzle this would be, so if anyone wants to correct the tags, feel free. Imagine you ...
1answer
223 views

### What is the maximum number of allies that you can have in this scenario?

There is a military/diplomatic crisis, with many sides involved. Your goal, as an uninvolved party now entering the conflict, is to get as many allies as you can. You make an ally by supporting a ...
1answer
316 views

### Using burning ropes as timers

This puzzle is an harder version of a very famous one. It has been asked many times on PSE, but this time the question is slightly different (1) (2). So please read this question twice before marking ...
0answers
185 views

### A Logician's Game of UNO Flip

Two players are in the middle of an ongoing one-on-one game of UNO Flip, with all its standard rules in effect. Play is currently Light Side Up. It is Player B's turn. Player A has 3 cards remaining, ...
1answer
400 views

### Latin-Square Adjacent Puzzles

Here are two $5 \times 5$ Latin-Square Adjacent puzzles. For each cell, put a digit between $1$ and $5$ such that: Each row and column contains one occurrence of each digit $1$ to $5$. If two cells ...
4answers
3k views

### Guessing hat colors

Red or Black There are 3 children sitting on three chairs. The children can only look forward and all wear one hat. The hats are either black or red. They are a total of 5 hats, 3 are colored red and ...
3answers
224 views

### Linking Cars on a Track going at Different Speeds

A kid places three model cars on a long, straight track equally spaced apart. He sets each of them to a different speed (though he forgot the specific speeds). These cars are special, though: they ...
0answers
67 views

### The king, the princess, the 3 wise men, and the 3 x's [duplicate]

A princess just became of marriageable age, and her father went out to get 3 wise men. He placed them at a round table and wrote either an X or an O on each of their heads, writing in such a way that ...
4answers
4k views

### Men digging holes

Suppose 9 men take 9 hours to dig 9 holes in the ground. (a) How many hours would it take 3 men to dig 3 holes? (b) How many men would it take to dig 54 holes in 54 hours?
1answer
258 views

### Is Every Obtuse Angle A Right Angle?

The Journal of Irreproducible Results once posted an article saying that every obtuse angle is a right angle. Their argument follows below: Given the obtuse angle $x$, we make a quadrilateral $ABCD$ ...
1answer
169 views

1answer
125 views

### Find the lowest floor from which Venus eggs break [duplicate]

Venus gave you two eggs because she wants to test their strength. She lives in a 100 floor building and she wants to find the first floor above which the eggs break when thrown out of the window. ...
1answer
146 views

### Mathmatical equation answer [closed]

I think there must be a way to solve this but I can't get there Green + Blue = Yellow Red + Green = Purple Yellow - Purple = Red Red + Green + Blue = 9 I have made some progress And but I run ...
1answer
124 views

### Perambulating ants 2

The ants from this puzzle have been placed into a new arena: a cross-shaped hallway with a pillar (black square) in the centre and four statues (numbered 1-4) set symmetrically. The ants, like last ...
3answers
898 views

### Super Secret Cookbook

You requested the password for a super secret cookbook and received an SMS with the following content: 77733666688833 2555555 777772222337777 2663 777337555222233 84433 6688622337777777 9444844 ...
1answer
149 views

### 8-puzzle in 12 steps

This quiz is about the 8-puzzle. It is a board with 9 spaces. There are 8 tiles with the numbers 1 through 8. One space is empty (.). You slide the tiles around the ...