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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15
votes
5answers
1k views

Creating the hardest 10x10 maze

You are given an empty 10x10 grid. You are allowed to paint some of its cells as walls (black), while the remaining cells stay empty (white). A robot is programmed to start in the top-left corner of ...
2
votes
1answer
59 views

How to understand this line in the solution to this puzzle?

I'm trying to understand the solution to a puzzle named "Expelled," the link to which is here. Most of the solution to the puzzle makes sense to me, except the most important part -- how to determine ...
3
votes
1answer
81 views

It's all in the 2's follow-up question

This is in regards to the solution in Slitherlink - It's all in the 2s I know it may seem dumb, but I don't understand the logic behind the second 2 chain in the solution. To help provide clarity ...
4
votes
2answers
259 views

Creating the hardest 7x7 maze

This puzzle is based on Creating the hardest 6x6 maze You are given an empty 7x7 grid. You are allowed to paint some of its cells as walls (black), while the remaining cells stay empty (white). A ...
9
votes
2answers
140 views

Cut It Up! (then find a phrase)

This is a "sorry for messing up yesterday's clues" puzzle. For each shape below, divide along grid-lines into identical pieces (rotation and reflection allowed). The first shape has 3 pieces, and the ...
22
votes
1answer
829 views

Hey, This is a 100th Puzzle of Mine!

Yep, this is my 100th puzzle here in PSE~ I'm really having a wonderful time here, thank you so much guys! >< I planned to write a harder and bigger one, but it turned out I was too lazy to do that....
12
votes
1answer
479 views

Slitherlink - It's all in the 2s

Can you solve this Slitherlink puzzle that I came up with? And in CSV: 3 - 3 - 2 - - 2 - 2 - 2 - - 1 1 2 2 1 - - 2 - 2 2 - - - 2 - 1 2 - - 1 - I tried to ...
26
votes
4answers
4k views

Creating the hardest 6x6 maze

You are given an empty 6x6 grid. You are allowed to paint some of its cells as walls (black), while the remaining cells stay empty (white). A robot is programmed to start in the top-left corner of the ...
-1
votes
0answers
59 views

Deducing Puzzles [duplicate]

There are some puzzles , where it is very difficult to find the solutions and many will probably think that there are no solutions . But actually solutions are hidden as clues in the puzzles . Here ...
48
votes
10answers
4k views

Clever Jack - A logical fairy tale

As so often happens in fairy tales, there once was a king who had an intractable problem, one that even his wisest advisers could not solve. After many years of frustration, the exasperated king ...
16
votes
9answers
4k views

Three boxes, Four questions, Three times not true, Once the truth

There are 3 boxes, only one of which contains a treasure. The guardian will only answer you truthfully once, the other three times he will lie. You may ask 4 YES or NO questions. Which questions ...
1
vote
2answers
279 views

The Missing House Number

The Visit One day I was visiting my sister in Boston and heard a bunch of kids yelling and playing in the yard ( yahd ). I couldn't see the kids, and hadn't seen my sis for years so I asked her, "...
5
votes
3answers
1k views

Puzzle to test IQ

I've been figuring for this quite some time. Hope someone can help me out.
11
votes
3answers
245 views

EDUCATION becomes a pandigital number

Each of the letters of the word EDUCATION is assigned a different integer value between 1 and 9, for a total value for the word of 45. With the same value for each of the letters, the total values of ...
15
votes
3answers
296 views

Curve Data: A-hint for A-thin

I just recently know about Curve Data puzzles from Logic Masters India. Here I tried to write two simple puzzles to introduce them to you. They should be easy though as I still can't write a harder ...
2
votes
1answer
263 views

What is the solution to this matrix reasoning puzzle?

It is from http://www.programaths.com/iqchallenge/index.php And one of the last items i didn't have any clue what is the solution I know the answer but the solution and the reasoning to it i can't ...
18
votes
0answers
516 views

What is the Color Code™?

Inspired from Can you name the country code? and What is a Number™? series $ \begin{gather} % custom template - reuse if you may \def\S#1#2{\Space{#1}{21px}{#2px}}\def\P#1{\V{#1em}}\def\V#1{\S{#1}{9}}...
23
votes
2answers
1k views

New logical puzzle

The goal is to divide the grid into regions of exactly four cells (tetromino). Each region contains exactly two different symbols. Regions of the same shape must contain the same symbols. The ...
3
votes
4answers
185 views

Mensa Pattern recognition riddle

I have a question about the solution of this pattern recognation task: I know that according to the book where I it found the correct answer is E. The "argument" is: Vertical lines represent $1$ ...
8
votes
4answers
427 views

Reconstructing the results of a 4-team soccer tournament

4 teams play in a "round-robin" soccer tournament, in which each team plays each other team once. Each game has 3 possible outcomes: team 1 wins, draw, or team 2 wins. The winning team receives 3 ...
6
votes
1answer
361 views

My friend's dad gave her a puzzle to solve, and I've never seen anything like it, any help would be greatly appreciated

I am admittedly not a puzzle person, but I have never seen anything like this, and I am at a complete loss. I have spent an embarrassing amount of time on some weird theories. Any help would be an ...
29
votes
2answers
1k views

Reverse Puzzling 2

This puzzle was inspired by Dr Xorile's first reverse puzzle! Kudos to him for coming up with such a fun format. Intrigued, I gave George yet another famous puzzle to ponder over. Once again, I was ...
0
votes
0answers
80 views

Haircut in an imaginary town [duplicate]

An imaginary town has 2 barbers one of them has a great haircut the other one has a bad haircut whom should you get a haircut from ?
7
votes
1answer
110 views

Number to Alphanumeric Mapping

A certain website uses the following mapping to encode their integer ID to an alphanumeric string. Can you figure out what the mapping is? ...
14
votes
2answers
422 views

(Indonesian) Fill-In Puzzle

I made this seasonal puzzle to celebrate the upcoming Eid al-Fitr in Indonesia. So actually there are four thematic hidden phrases that can be found after solving the puzzle. But because they are ...
3
votes
1answer
187 views

A graph logical task - Ramsey theory

I have the following puzzle and I want to check if the answers that I gave are correct. You can check also my reasoning behind the answers. The puzzle is: In a perfect world two people are either ...
13
votes
2answers
583 views

Sudoku variation: Using various chess moves, solve the grid from just two numbers

I've been watching a youtube channel hosted by puzzlers and attempting the sudoku variation they post each day. Today's I found particularly interesting and while sharing it around it proved quite the ...
10
votes
2answers
302 views

Alice, Bob and Charlie know the sum, product and the difference between two numbers

This was sent to me by a friend so I can't source it but here's the full text: Three Mathematics students, Alice, Bob and Charlie have to find the values of $x$ and $y$, with $x, y \in \mathbb Z, ...
5
votes
2answers
223 views

Achieve the best outcome by a tactical statement

This puzzle is taken from Schelling's Game Theory: How to Make Decisions by R.V. Dodge, in which bargaining power is gained, paradoxically, by burning bridges and removing options for oneself. Here it ...
4
votes
1answer
174 views

Cutting a Rectangular Board

There is an $m \times n$ rectangular board drawn on a graph paper. You need to cut it into $mn$ $1 \times 1$ squares by straight cuts along the grid lines. You are allowed to stack several pieces ...
13
votes
9answers
28k views

Mensa Norway last 3 questions

I had no problems with solving first 32 questions from http://test.mensa.no but the last 3 questions are totally bugging me out even knowing the answers. Could anyone help me getting the logic behind ...
8
votes
3answers
888 views

Find the burglar by covering all the streets

There is a burglar in a neighborhood and the police officers are trying to find him. But there are limited amount of police, namely 4 of them, who could cover the streets. Could you place our ...
27
votes
7answers
5k views

Unexpectedly Difficult Matchstick Problem

The words say: 听说只有智商高达200的人才有办法打出来 (only people with 200 iq can solve this). 只移动1根火柴让算式成立 (move only one match to satisfy the equation) note: it is not my puzzle and i do not know the solution
6
votes
4answers
202 views

Find a sufficient passcode

"As per corporate policy we need to change the passcode for the building's entrance every six months," said Lionel. "Your job is to pick the new passcode. It must have at least four numbers in it." ...
6
votes
0answers
73 views

How can I create written logic puzzles with multiple variables and the fewest number of clues?

When I refer to written logic puzzles, I mean those in which, for example, 5 men wearing 5 different colors of aprons are bringing 5 different pies from 5 different cities to 5 different booths in the ...
4
votes
1answer
101 views

Finding the Missing Word in a Crossword

On each of the 25 cells of this board, place one of the letters A, C, M or S so that, in alphabetical order, nine of the ten words that can be read down or across are the following: AACAC AMCAS ...
7
votes
1answer
264 views

New maths puzzle

The objective is to blacken certain boxes. The numbers outside represent the sum of the numbers contained in the white boxes in the corresponding rows or columns.
4
votes
1answer
114 views

Smudged Sudoku - help me solve it!

One late evening I was making my sudoku. I finally finished until water spilled all over the middle-right block. The only thing I remember is the numbers present in the block (but not their position):...
8
votes
1answer
196 views

Puzzle of the day - Sudoku Rossini

The arrows outside the grid indicate that the nearest three digits in the corresponding direction are in ascending or descending order (the highest number is always in the direction of the arrow). All ...
5
votes
3answers
328 views

Shocks and guesses

The Liar, the Random and Truth teller were captured and brainwashed to forget whether they always lie or tell truth or randomly answer.Everyone is handcuffed to a chair and gagged with gray, white and ...
9
votes
2answers
938 views

Sudoku Help: Hard

I am unable to finish this Sudoku. All numbers are verified by the app. I'm sure there must be a way to solve this without guessing. Even an online tool couldn't tell me a next number.
9
votes
1answer
218 views

Simon Tatham's Gokigen Naname

Lately, I've been interested in Gokigen Naname a.k.a Slalom a.k.a Slant. Luckily, Simon Tatham has a generator for Slant. Usually, the generated puzzle is so-so, but this particular generated puzzle ...
4
votes
4answers
728 views

Give me a clue!

Create a Nonogram / Picross which cannot be solved uniquely without giving at least one clue. That is, without prefilling at least one field in the puzzle there exists multiple valid solutions. The ...
9
votes
1answer
667 views

Weird and complex puzzle that we need help with

So basically this is a complex deep web puzzle and we're pretty much stuck at it right now as we don't have any idea what this is about, any help will be aprreciated (the attached images are the ...
1
vote
5answers
198 views

A couple have 9 children, half of children are boys, how? [closed]

My friend asked me the puzzle, A couple have 9 children (none of them were adopted) Each child must be either a boy or a girl Half of that couple’s children are boys How that can be ...
19
votes
2answers
913 views

Tic tac toe - Sudoku: A variation in which the centre box defines the layout of the other boxes

I stumbled across this interesting variation of Sudoku the other day and thought I'd give it a try, it has however baffled me and I've been unable to progress past the very early stages. The puzzle ...
6
votes
1answer
210 views

Logic puzzle about six college freshmen

I found some logic puzzles on someone's blog from a few years ago, and have been trying to solve them. Here's the link to the page: https://hedgehogcomms.blogspot.com/2015/04/puzzling-over-logic-...
-10
votes
1answer
105 views

N-1 queen on the chessboard

You are trying to solve the famous N queens problem. You broke one of the queens from your chess pieces collections. Now, you have created the following puzzle: You are given an N*N chessboard. Is ...
2
votes
1answer
125 views

Logic grid puzzle

I found some logic puzzles on someone's blog from a few years ago, and have been trying to solve them. Here's the link to the page. Please let me know if you have any suggestions! I have looked at ...
13
votes
1answer
427 views

Tapa - Confluence

This is a Tapa puzzle. Rules of Tapa: Shade some cells of the grid. Shaded cells should form a single [orthogonally] connected group; no 2×2 square should be fully shaded. Some cells have ...

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