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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6
votes
2answers
652 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
196 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 ...
5
votes
2answers
181 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 ...
9
votes
3answers
187 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\\\...
6
votes
2answers
223 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
12
votes
1answer
166 views

Masyu-making game

Two players are playing a game on a $4\times4$ board. The players take turns adding either a white circle or a black circle into any empty square, so that the board makes a solvable masyu puzzle (with ...
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
360 views

Who is Paul's girlfriend?

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

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

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
224 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
179 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. ...
5
votes
2answers
113 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 ...
14
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 ...
2
votes
2answers
202 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
244 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
789 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
725 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: ...
0
votes
0answers
56 views

Word problem help regarding Sin and angles [closed]

My teacher gave me this problem. There is a triangle with angle with 30 degrees (so opp/hyp = 0.5) This specific triangle has an area equal to it's perimeter. All I got furthest to was that hyp is ...
2
votes
0answers
94 views

What should be the missing number? [closed]

What would be the missing number?
8
votes
5answers
771 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
175 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
115 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
247 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/
11
votes
1answer
1k views

The three greedy pirates

Her eyes lit up as the pirates Sparrow, Barbossa and Turner opened the treasure chest and saw the mountain gold coins. After pirate's tradition, Sparrow first took a coin, then Barbossa two, ...
4
votes
3answers
181 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
107 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
46 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
469 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
124 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
97 views
56
votes
13answers
17k views

Are there eighteen or twenty bars in my castle?

Two friends, Mark and Rose, are very famous logicians; they are so clever that they can deduce any logic connection possible in a matter of minutes even from the most vague situation. Unfortunately, ...
2
votes
1answer
112 views

Deduce Distinct Digits of the Given Fibonacci Sequence- Detail all Steps

$DEPUS$ $SRST$ $UDQD$ $CTQU$ $DTPR$ $PQR$ $SDE$ $VRR$ $CVV$ $DUU$ $QP$ $TT$
3
votes
1answer
157 views

Valiant Knight is back..but he is in grave danger from the Evil Queen

King has placed a bounty on Valiant Knight and enlisted his evil queen’s help. Queen knows knight’s regular stops of his journey and knows he goes through all odd prime cells. She strategically ...
21
votes
8answers
3k views

Robots in a spaceship

Xerxes has 6, 7 and 8-arm robots in his spaceship. Unfortunately, the 7-arm robots are misprogrammed and everything they say is a lie. The other robots are fine, they always speak the truth. Once ...
0
votes
1answer
74 views

How do you make Prime “COMPUTERS”?

$Given$: $COMPUTERS$ is the smallest Pan Digital containing all the digits 1 to 9 occurring only once. $COMPUTERSV$ is a Prime only when one of the correct digit ($V$)is added at the end. Also, $...
14
votes
2answers
688 views

The alcoholic village festival

The villages Arriba and Abajo together have 2019 inhabitants. At the annual festival are more than 2000 villagers this year. When they form a huge circle for dancing, everyone calls happy: ...
7
votes
2answers
234 views

Listen to my Story…Let us find the Unique Invisible Pan Digital Pair

I was an avid reader of Popular Science magazine. In the last page or so, they usually had visual clues without words to make useful stuff. I always wanted to create a mathematical puzzle like that ...
4
votes
4answers
428 views

Simple logic puzzle

We think of an island inhabited by rogues and knights. Rogues are always lying, knights always speak the truth. One day 12 islanders come together among which is at least one knight and at ...
2
votes
1answer
99 views

All Aboard..Hop onto the Power Train to reach Destination Unity

Your goal is to reach the destination unity. starting from $3462$ with three intermediate stops. You are allowed to use only 2 mathematical operations..multiplication and Exponentiation. All the ...
5
votes
3answers
168 views

When is the truth spoken?

A thief speaks truth two days a week alternatively ( T F T ). The days are the same for each week. The thief gives these statements on 3 consecutive days : D1 : I lie on Monday and Tuesday. D2 : It'...
15
votes
3answers
2k views

The warming up game

The theater group began today with a warming up game. Everyone has been assigned a role and is now either a bad guy who always lies, or a good guy who always tells the truth. Max, who comes late, ...
2
votes
1answer
68 views

Primes from the Pan Digital

Pan Digital Number is the smallest with all the digits 1 to 9 with no repeats. When looking forwards or backwards, eleven Primes can be extracted from that number preserving the same sequence. Among ...