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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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
732 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
244 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
105 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
188 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
74 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
153 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
207 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
460 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
108 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
134 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
348 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
120 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
330 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
102 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
359 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
101 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
56 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
125 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.
5
votes
1answer
114 views

Red and Blue Dividing Line

In the grid shown below, 20 numbers are given in blue and red. Draw a dividing line along the contours of the grid such that A) Blue Numbers Sum to the same on both sides of the line B) Red Numbers ...
2
votes
1answer
133 views

Mystic Island Math - Can you Figure it out?

On Mystic Island math is done via symbols. Distinct symbols represent distinct digits, varying from 0 to 9. From the picture below, figure out the corresponding digits. Please provide your reasoning....
-3
votes
2answers
139 views

How do you Solve an Age-Old Problem? [closed]

Mansion has a son (Mark) and a daughter (Mindy). Mark is older than Mindy. Five years ago, Sum of Mark and Mindy’s ages was twenty two. Five years from now, Mark will be exactly twice as old as Mindy....
1
vote
3answers
214 views

Jack and Jill went up the Hill to play

A Simple Card Game. This deck of cards has only four cards simply labeled 1, 2, 3, 4. They are placed face down. Jack and Jill take turns to draw a card. You sum up the numbers drawn so far after ...
8
votes
1answer
232 views

Riddle to Code 2: The return of numbers

The first is a pirates favorite letter. The second is from a famous quote of shakespear. The third is squaring it off in a famous formula. The fourth is the first in a very well known song. ...
-5
votes
1answer
93 views

Express 50 to 100 with constituent digits only…my 100th pzl on 50th day

Using the following rules only, Express the numbers from 50 to 100 using only digits in the number. Concise with minimum number of characters is preferred. No concatenation of numbers allowed. Only, ...
2
votes
2answers
145 views

Find the “X “in the Box

Interlocked Rings shown in the picture share a common sum of 28. The numbers to be filled vary from 1 to 12 and do not repeat. Already four numbers..8, 9, 10, 11 are placed. Fill the X s with rest ...
9
votes
3answers
4k views

Too early in the morning to have SODA?

Each letter shown represent distinct digit...can vary from zero to nine. $COCA$, $COLA$, $SODA$ are three concatenated numbers. Figure these out from the following relation: $COCA + COLA = SODA$
2
votes
2answers
79 views

All the Signs point to the Second Prime…Figure out the Missing Digits

$Given$ The six Interrelated Equations A, B, C, D, E, F All equal to 3. Allowed Digits.. 1 to 9. All the missing 9 are distinct...9?s...9 Different Digits Fillin all the digits that satisfy all ...
2
votes
3answers
196 views

16 people, make 3 consecutive round of 4 players

I am struggling with this issue for a tournament I am planning. Take 16 people. Consider a 4-player game. To be clear, in each round all 16 players must play the game once. I want to make at least 3 ...
11
votes
4answers
2k views

Can you open the door or die?

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: There are 66 green and 66 blue door cards on the ground. If you ...
8
votes
1answer
690 views

I am caught when I was about to steal some candies

I am a eight years old boy, I love candies, but my mom does not want me to eat any more candies because I start to have black teeth :( but I still love candies so... Today when I was about to steal ...
3
votes
2answers
362 views

Is it True that Two + Two = 2? If so, what is Ten + Ten and Nine + Nine?

Given: SIX + ZERO = 4 TWO + THREE = 15 FIVE + SIX = 88 ONE + TWO = 83 TEN + TWO = 13 If so, is TWO + TWO = 2 correct? What is TEN + TEN ? NINE + NINE ? Hint 1
14
votes
3answers
8k views

The Harry Potter Potions Riddle

A simple riddle from the first Harry Potter book. You are in a room with seven potions. There is a doorway ahead and a doorway behind, both engulfed in flames. Which potion will allow you to move ...
5
votes
2answers
159 views

Please figure out this Pan digital Prince

Given: P, R, I, N, C, E, T, O, M are all distinct digits varying from 1 to 9. PCRON, PRINCETOM are two concatenated numbers. PCRON is the highest possible number you can have fulfilling the ...
10
votes
1answer
249 views

Next date with distinct digits

The date today is 7th June 2019, or 07/06/2019 (using the English DD/MM/YYYY ordering). When is the next date that when written in this way has all eight digits different?
0
votes
1answer
129 views

Don’t let this daunting equation dissuade you to deduce the desired result

Given: A, B, P are distinct digits. AA, AAA, ABB are concatenated numbers. Relations: $$P=A+A+B$$ $$(AA + ABB)^P-(ABB)^P=(AAA - A) ^P+(B+B^B*B)^P+(B^B)^P$$ Don’t be afraid to make reasonable ...
9
votes
2answers
621 views

Six liars, truth-tellers and jokers

As in this puzzle, there are three different kinds of people: truth-tellers (always telling the truth), liars (always lying) and jokers (who may either tell the truth or lie). Based on these aspects ...
6
votes
2answers
296 views

$1$ of $100$ Homes

On Crossfield Housing Estate, there are exactly $100$ homes numbered from $1$ to $100$. Rook is living in one of them. Kaito hasn't met with him for a long time and wants to pay a visit. Here is some ...