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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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8
votes
2answers
749 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
120 views

What should be the missing number? [closed]

What would be the missing number?
8
votes
5answers
777 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
225 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
135 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
342 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
200 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
119 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
54 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
522 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
138 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
110 views
56
votes
13answers
18k 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
121 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
172 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
81 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
738 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
245 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 ...
2
votes
1answer
106 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
192 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
75 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 ...
7
votes
1answer
155 views

The strange forest

In the forest of change there are strange creatures: 17 puzzs, 55 lings and 6 stacs. If one species meets the other, then they become the third. For example: If a puzz meets a stac, then they ...
3
votes
2answers
212 views

Help me solve this question from a culture fair IQ test? [closed]

Cannot wrap my head around these 2, please also tell me what the logic is? For the 2nd one I think it might be a water droplet shape? But not sure about the logic. Thank you
12
votes
1answer
461 views

Resolve this Fibonacci Relationship

$Given$: $A$, $B$, $C$, $E$, $F$ are distinct digits varying from $1$ to $9$. $A$ is a Fibonacci number. $BB$, $BC$, $EF$ are concatenated Numbers. $Relationship$: $(A*BB)*(BC)^2$ = $(EF)^2- B$ ...
-7
votes
4answers
131 views

What am I to A? | Riddle

If teresa's daughter is my daughter's mother, what am I to teresa? Grandmother Mother Granddaughter I am teresa
3
votes
1answer
112 views

Fill 5 x 5 grid

In each cell of a 5 × 5 square there is a token that is black on one side and white on the other. Initially all tokens are placed with the white side facing up. On each move three tokens in ...
18
votes
2answers
1k views

Miss Toad and her frogs

Miss Toad owns a lot of frogs. These frogs are all looking the same, but they can be either mad or nicely. If a mad frog is in a room with 3 nicely frogs, then he turns red, because he is ashamed. ...
3
votes
2answers
135 views

Badminton in vacation

During their holidays Martina, Karl and Jim played badminton every day. The winner of each match continues to play in the next match against the one who just had a break, while the loser of this ...
2
votes
2answers
349 views

How many codes are possible?

The line - codes we are looking at consist of black and red lines. These lines can have width 1 or 2. Black and red lines are taking turns, black line, red line, black line, ... The code ends and ...
2
votes
1answer
104 views

Resolve these Highly Narcissistic Relations

$U$, $V$, $C$ , $D$ , $E$, $F$, $G$, $H$, are distinct digits, varying from 1 to 9. $UVCD$, $EFGHD$, $EHHEV$ are concatenated numbers. Please deduce these with concise reasoning from the given ...
3
votes
1answer
101 views

Take out one Third..Keep Two Third..To Total Ten

There are total 36 numbers in the grid shown in the picture. Cross out 12 of them and keep 24 of them. Sum of the rest of the numbers should total 10 for each row and column.
2
votes
1answer
121 views

Help the IT guy heal one of his hard drives [duplicate]

There are $64$ hard drives each with one extra bit ("flag"), the value of which you don't know (it can be '$0$' or '$1$'). One hard drive is infected with virus that you need to heal. You have two ...
-6
votes
1answer
72 views

Give these Digits their own Place..Place them Right

In their own Circle. Such that the arrows point to successive numbers . Start with 1 and end with 9. There might be more arrows than necessary. Find the solution with least number of arrows ignored.
0
votes
2answers
86 views

It is not as Simple as it Looks to get the right Alignment

Of these US Coins (Quarter and Dime Combo). Initial arrangement of the coins as shown in the picture is as follows... Q D Q D Q D Q Objective is to attain the final configuration... Q Q Q Q D D D. ...
3
votes
2answers
335 views

5 cars in a roundabout traffic

Five cars are driving in a roundabout traffic at the same moment. Each comes from an other direction, and drives less than one full round. Also each car leave the roundabout traffic in an other ...
4
votes
1answer
103 views

Numbers 1 to 10 in the circles

The objective is to enter the numbers 1,2,3,4,5,6,7,8,9,10 in the blue circles. Doing this, the sum of the numbers has to be equal in the three connected rectangles (a rectangle consists of 4 ...
6
votes
2answers
361 views

Go Get the Six Six-Pack

And fill with right Mathematical operands and enjoy. Six Relations shown in the pictures are missing the right operands. You can only use plus, minus, multiplication, division signs in between the ...
-1
votes
2answers
102 views

3 guys play frisbee [closed]

Story: Three guys A, B and C meet daily to play frisbee. They determined: Always if A doesn't have a frisbee, then B has one. If B doesn't take along a frisbee, then C has one. Today B hasn't ...
5
votes
1answer
92 views

A Prime Length Rope into Prime length ropes

We have a rope with a prime unit length, and we need to divide this rope into $9$ ropes by cutting it with prime and/or 1 unit lengths. After cutting the rope, you are supposed to find any kind of ...
4
votes
1answer
57 views

Deduce the Missing Digits from the given Relations

Picture shown below contains 3 horizontal and 3 vertical relations. Digits to be filled vary from 1 to 9. Order of operations is given following the arrows vertically and horizontally.
-4
votes
2answers
126 views

Be Quick and Calculating..Take Four Shots

To Target Sum of 100 Exactly . By shooting the right different numbers in four shots summing upto 100.