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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19
votes
2answers
1k views

Heyawake: An Introductory Puzzle

This is a Heyawake ("divided rooms") puzzle. Rules of Heyawake: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected. ...
10
votes
3answers
337 views

Black to play and win (Teeko)

$$\def\S#1{\phantom{\Space{18px}{22px}{0px}}\llap{#1}} \begin{array}{|c|c|c|c|c|}\hline \S{}&\S{}&\S{}&\S{}&\S{}\\\hline \S{}&&&&\\\hline \S{}&&X&O&X\\\...
3
votes
1answer
271 views

Missing Number in a Seven Segment Circle

What number should replace the question mark? Please be helpful. If you have the answer, please reply to this post with the explanation and answer. If you don't have the answer, then don't comment. ...
19
votes
5answers
1k views

Single Colour Mastermind Problem

Imagine we're playing a game of mastermind with the usual eight colours, only this version has six holes across in which to place colours. And to make it easier for you I tell you that I have filled ...
7
votes
2answers
711 views

Bongard n°4: Neutral vs Town

This is my last puzzle before the holidays, have a nice summer everyone. Here's a link to the rules of these kind of problems: There are six boxes on the left, and another six on the right. The ...
-5
votes
1answer
171 views

A riddle from Candy Cadet [closed]

I am Candy Cadet, come get your candy here. I have candy all day, everyday. Candy. Candy. Candy. Now I will tell you a story about a young woman who was sealed in a small room. In the room was a ...
10
votes
1answer
517 views

Can you solve this masyu puzzle?

Hey guys, enjoy this masyu puzzle! For those unfamiliar with masyu, here are some instructions: The goal of Masyu is to connect the circles on the grid via a line that closes itself and also does ...
18
votes
1answer
948 views

A Total Masyu puzzle

In a Total Masyu puzzle, one must draw a single loop through the centres of some cells according to the following rules: The loop may only travel horizontally or vertically, never diagonally; all ...
17
votes
5answers
3k views

Help me, I hate squares!

There is $5$x$5$ equidistance matrix dot given as below; You need to remove dots from the figure where it will be impossible to form a square by drawing lines between dots at the end. So what is ...
1
vote
1answer
86 views

Seed is to sprout as [closed]

I came across this question and couldn’t find an answer to it. The question goes like so: Seed is to sprout as A. Plant is to grow B. Garden is to weed C. Dawn is to morning D. Teenager is to ...
16
votes
1answer
412 views

Statue Park: Apollo 11

This is a Statue Park puzzle, made in honor of the 50th anniversary of the Apollo 11 mission. Rules of Statue Park: Shade some cells of the grid to form the given set of pieces. Pieces may be ...
11
votes
2answers
3k views

The grades of the students in a class

You are a new Math 102 professor in a university class of 88 students and would like to learn their grades from previous semester to know your students better and put a note of it to get an idea how ...
6
votes
5answers
890 views

Violations of the law

I live in A but work at B. The two are 45 minutes apart and I could commute back and forth either by driving or by taking the bus. Every day, before going from A to B in the morning and before going ...
8
votes
1answer
195 views

Yajisan-Kazusan: Diagonal Arrows

This is a Yajisan-Kazusan puzzle. Rules of Yajisan-Kazusan: Several numbered arrows are given in the grid. Shade some cells so that: no two shaded cells are adjacent unshaded cells form ...
6
votes
2answers
272 views

Top Game Developers

Top Game Developers Back Story Okay fellow puzzlers, I hope you packed your lunch, this one is my most challenging puzzle to date... Johnny is writing an article about some of the top-selling ...
30
votes
5answers
6k views

Two spies throwing stones into a river

There is a puzzle about two spies: Two spies must pass each other two secret numbers (one number per spy), unnoticed by their enemies. They have agreed on a method for doing this using only 26 ...
6
votes
2answers
703 views

Legal advise for a family dilemma

"A client of mine," said a lawyer, "was on the point of death when his wife was about to present him with a child. I drew up his will, in which he settled two-thirds of his estate upon his son (if it ...
1
vote
2answers
239 views

Minesweeper challenge #4

While solving another Minesweeper puzzle, I ran into yet another unsolvable corner. Well, actually, this time I have two unsolvable corners in the same puzzle. Here's the bottom left corner: ...as ...
4
votes
2answers
217 views

Minesweeper challenge #5

Coming back to another Minesweeper challenge... I've run into another "unsolvable corner" (corner of a puzzle where there isn't enough information to be 100% certain that any particular square that ...
6
votes
2answers
263 views

The CompuTaria Quest - A young Wizard's journey

Once Upon A Time In A Land FAR, FAR Away... Our adventure begins in the enchanted land called "CompuTaria". You are, "Binaryian" a 3rd year Wizard In Training. Today began like any other day - you ...
11
votes
7answers
2k views
36
votes
2answers
6k views

Escape the dungeon, by deciphering the codes and navigating the rooms to find a way out

You have been thrown into a dungeon with many rooms; you don't know who did this or why. You start in room 37. You might be thinking "Why 37?", so I will explain this: "Why not?" You need to find ...
2
votes
1answer
376 views

Who is Paul's girlfriend?

Persons: ...
-3
votes
1answer
909 views

we are five we have three thousand four hundred fifty who are we? [closed]

we are five we three thousand four hundred fifty, who are we ?. Its a riddle like question but stranded with getting the answer for this question , am very sure the answer will make me slap my head ...
7
votes
2answers
316 views

Nono-cube - Ultimate Puzzle Giant

Prologue - Instructions Shamelessly copied and pasted the following from @jafe's puzzle :P This is a three-dimensional nonogram. The first square gives the enumerations for the Z-axis, top to ...
3
votes
2answers
268 views

5 Precommitting Pirates Puzzle

Another variant of the Pirate Puzzle, inspired by this variant and a bit more complex. Scenario: Five pirates of different ages obtain 100 gold pieces in total, and want to decide how to split them. ...
6
votes
2answers
219 views

3D Nonogram - Spinoff of the Reboot

This puzzle is inspired by recent 3D nonogram puzzles by Jafe and Omega Krypton. Check those out if you want, but they are not required to understand this puzzle. This 3D nonogram has clues with two ...
15
votes
4answers
1k views

What does my girlfriend want me to buy for her?

I'm obviously dating up, because I can't figure out what my girlfriend wants me to buy her for Christmas. When I asked her what she wanted, she gave me the three puzzles below. The only hint she gave ...
1
vote
2answers
269 views

Minimize sum of guesses to win lottery

Ten boxes are given with $a_1,a_2,a_3,a_4,a_5 ......a_{10}$ number of balls in them respectively .These boxes are randomly ordered but $a_1,a_2 .....a_{10}$ is told.We can arbitrary select a box and ...
5
votes
1answer
312 views

5 Negotiating Pirates Puzzle

5 pirates of different ages have a treasure of 100 gold coins. On their ship, they decide to split the coins using this scheme: The oldest pirate proposes how to share the coins, and ALL pirates (...
8
votes
2answers
1k views

5 Pirate Puzzle Question

Question: 5 pirates of different ages have a treasure of 100 gold coins. On their ship, they decide to split the coins using this scheme: The oldest pirate proposes how to share the coins, and ALL ...
8
votes
2answers
753 views

IX-NAY on the IX-SAY

Will this sequence ever have a 6 in it? 9, 1, 1, 1, 10, 3, 1, 1, 10, 5, 1, 1, 10, 1, 5, 2, 1, 1, 10, 1, 1, 1, 5, 4, 1, 1, 10, 3, 1, 1, 5, 1, 1, 1, 5, 2, 1, 1, 10, 5, 1, 1, 5, 3, 1, 1, 5, 4, 1, ... ...
6
votes
3answers
2k views

A dozen into six rows?

You were given 12 coins by your friend. He bet that if you could arrange these dozen coins into 6 rows of 4 coins such that it makes two similar shapes, he will give you 12 more coins. How will you do ...
20
votes
5answers
5k views

Can you open the door or die? v2

This is the follow up question to my previous question You wake up and find yourself in a very strange room with a single door. You find a note on the ground surrounded by lots of cards: ...
2
votes
0answers
126 views

What should be the missing number? [closed]

What would be the missing number?
8
votes
5answers
780 views

The distance between David and Eric

Alice and Bob are looking at each other, both turn $10$ degrees and now they both can directly see Claire. If they continue turning in their same directions before, Alice will directly able to see ...
16
votes
9answers
7k views

Salesman's claim for mechanical keypad lock - 5 buttons and 545 combinations!

A company makes mechanical keypad locks. The keypad is a set of five buttons arranged vertically. O O O O O The buttons are quite close together. Once a ...
31
votes
8answers
10k views

How many cars does the millionaire have?

I had a logical riddle on a programming interview test which was something like this: In his garage a millionaire had cars, of which only 2 were not white, only 2 were not green and only 2 were not ...
12
votes
4answers
4k views

The joke office

Alice and Bob are supposed to get form A at the joke office. Forms A, B, C, D and E are each at exactly one of the following five terminals. At one Terminal is only one form. Terminal 1: Here ...
2
votes
1answer
232 views

The chariot race

In a chariot race only 4 cars came to the finish: the blue, the green, the red and the white one. Titus, who is in bed with a cold, inquires to Quintus about the outcome of the race, because he ...
2
votes
1answer
138 views

Oops! Mixed up Multiplication - Needs to be Fixed

$Given$: $U$, $V$, $C$ are distinct digits, varying from 1 to 9. $U$ > $V$ > $C$ $UVC$, $VCU$, $CUV$ are concatenated Numbers $(UVC)*(VCU)*(CUV)$ = $234235286$ The digits on the right hand side ...
5
votes
1answer
408 views

pattern recognition riddle

does anybody see in this pattern recognition riddle a reasonable solution? source: https://www.physicsforums.com/threads/visual-pattern-recognition-test.921583/
4
votes
3answers
202 views

Missing informations for the architect

An architect wants to plan the creation of a house, but he has only two perspectives, one from the left and one from the front. The house consists of concrete cubes. All concrete cubes must be ...
2
votes
1answer
123 views

What is the Last Digit in the Result of the given Expression? [closed]

$Given$: $ASC$ is a concatenated number with distinct digits. $S$ is square of $A$, $C$ is cube of $A$ Deduce the last digit of the following Expression through Deductive Reasoning only: $$\begin{...
1
vote
1answer
57 views

Pan Digital Split among Two Powers

$Given$: $AB$, $DBCE$,$AGFPQR$ are three concatenated numbers with all distinct digits varying from zero to nine. $AB^C$ = $DBCE$ $AB^F$ = $AGFPQR$ Deduce all the digits through logical reasoning ...
0
votes
0answers
87 views

IQ test question help [duplicate]

Can you help me with the solution of the matrix? It has been asked before here 2 but a valid and well explained answer was not provided. Source without answer: here
12
votes
4answers
528 views

Red and White Squares

There are two grid boards with the dimension of 9x9 and 14x14, consist of all white squares. You are supposed to color some squares with a red color on the conditions below: In a board, if two square ...
4
votes
3answers
141 views

Make 2019 Factorial Multiplication a perfect square

N is not a square number and consists of 2019 factorial multiplication as shown below: $N=1!\times 2!\times 3!\cdots 2018!\times2019!$ At least how many factorial needed to be removed from the ...
3
votes
5answers
2k views

Explain how 'Sharing the burden' puzzle from Professor Layton and the Miracle Mask should be solved

Two porters have to carry six pieces of luggage of unknown weight. Each piece weighs a different amount, and they are labeled in order of weight from A to F, with A being the lightest and F the ...
-5
votes
1answer
112 views

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