The Stack Overflow podcast is back! Listen to an interview with our new CEO.

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).

Filter by
Sorted by
Tagged with
1
vote
3answers
215 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
233 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 ...
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 ...
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: ...
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 ...
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 ...
4
votes
3answers
137 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 ...
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
622 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 ...
2
votes
1answer
134 views

A $3\times3$ ColorSaw

The pieces of this ColorSaw have been flipped, rotated and moved. Can you reassemble the puzzle so that each adjacent side has the same color/shape?
0
votes
2answers
127 views

A $2\times2$ ColorSaw

The pieces of this ColorSaw have been flipped, rotated and moved. Can you reassemble the puzzle so that each adjacent side has the same color/shape? Please explain your logic!
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 ...
33
votes
9answers
4k views

Winning Strategy for the Magician and his Apprentice

There are $13$ upside-down opaque cups and $2$ balls, a magician and his apprentice and yourself. You decide under which cups to put the balls, and the objective of the magician is to find the two ...
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
2
votes
1answer
190 views

Solve the pattern! (game)

Okay, so this is based off of https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/pattern.html And, my cousin made a random pattern and gave it for me to solve. Unfortunately, the logic is ...
3
votes
1answer
225 views

Happy New Year?

Extend this infinite series by five more terms: 17, 3, 5, 7, 11, 17, 2, 3, 5, 11, 13, 17, 2, 5, 7, 11, 13, 2
9
votes
3answers
624 views

A Mathematical Discussion: Fill in the Blank

I originally saw this on r/puzzles, and thought it deserved a place here. I have a solution to this puzzle, but it's really long and ugly. If anyone comes up with something simple, please share! ...
12
votes
1answer
391 views

Infinite Sequence based on Simple Rule

Using one simple rule, an Infinite Sequence has been developed. First 30 terms are given. Can you continue the sequence for at least next Ten Terms? Series continues from top left to bottom right. $...
15
votes
1answer
287 views

Statue View: 2, 3, 5, 7

This is another Statue View puzzle. It's easily the hardest of the three I've made, so I recommend trying the other two as practice first. Rules of Statue View: Shade some cells of the grid to form ...
0
votes
2answers
138 views

Do you know what's next?

'Predict' the next few (5 or 6) terms of this series. 1, 1, 1, 2, 3, 6, 7, 10, 11, 12, 17, ...? Hint: Who is the 'prime' suspect in this mystery sequence?
13
votes
1answer
285 views

Statue View: Raindrops

This is a Statue View puzzle, an original invention combining two logic puzzle genres: Statue Park and Canal View. It is harder than my previous Statue View, so you may want to start there. Rules of ...
21
votes
2answers
415 views

Statue View: Tetrominoes

This is a Statue View puzzle, an original invention combining two logic puzzle genres: Statue Park and Canal View. Rules of Statue View: Shade some cells of the grid to form the given set of pieces. ...
1
vote
1answer
154 views

Mensa 3rd Grade Recess Game [closed]

Mensa 3rd Graders At Recess There are dozens of variations of this puzzle type, but I put my own spin and characteristics to it. It is lunch time for the little ones at Mensa Mini's Private School. ...
6
votes
2answers
263 views

Liars, truth-tellers and jokers

In a strange village there are three kinds of persons: knights (always telling the truth), knaves (always lying) and jokers (who may either tell the truth or lie). A, B, C and D live in this village, ...
16
votes
1answer
519 views

Statue Park: Knight's Lines

This is a Statue Park puzzle. Rules of Statue Park: Shade some cells of the grid to form the given set of pieces. Pieces may be rotated or reflected. Pieces cannot be orthogonally adjacent (though ...
6
votes
1answer
363 views

The Most Powerful Number

A power-full number is defined as a number with $n$ amount of non-zero digits $D_x$. The number takes the form $D_n$&$...$&$D_2$&$D_1$. The digits in a power-full number satisfies the rule ...
7
votes
3answers
619 views

Three knights or knaves, three different hair colors

In a group of three people (A, B and C), everyone has a different hair color (blond, black or brown, not necessarily in this order) and everyone may be either a knight (always telling the truth) or a ...
9
votes
1answer
330 views

Statue Park: Five

This is a Statue Park puzzle (originally constructed for the 2019 24-Hour Puzzle Championship, as part of a Tarot card themed set -- no prizes for guessing which rank this puzzle was). Rules of ...
4
votes
1answer
247 views

Four Doors, One Escape

You are trapped in a room with four adjacent doors upon a wall. On each door is one of the first letters of the alphabet, in order, from left to right. You know that one of the doors leads to freedom, ...
0
votes
2answers
88 views

Uvc with Lots of Magic… Enjoy the Show!

Puzzling Weekend! UVc is back again with Lots of Magic... Enjoy the Show! Given: LOTS is being multiplied by F to yield MAGIC. Digit 0 to 9 are all represented by ten different letters in this ...
3
votes
2answers
137 views

Find the values of U, V, C based on the given relationship…useful for upcoming puzzles

Given: U, V, C are 3 distinct digits..values can vary from 1 to 9. CU is a concatenated number Solve for U,V, C from the following relationship: $U^V$ X $V^U $ = $CU $ This will give some basis ...
2
votes
1answer
102 views

Puzzling Palindromic Year with Pleasing Palindromic Expression.. Please find them

No computers, calculators or searches. Given: The number is a Palindromic year. $PQ$ is a concatenated number. $ U , V $ are two distinct positive integers Expressed as $ PQ ^ U + PQ ^ V + ...
2
votes
2answers
188 views

Cathy’s Composite party is powered by three Prime Pals. Can you find them?

Given: A, B, C are 3 distinct primes. Find the smallest composite number Y that satisfies the relation: $ Y = A ^ C + B ^ B + C ^ A $
0
votes
1answer
168 views

Every Answer To All Puzzles Here - Secret Found

BREAKING NEWS: The magic stone which reveals all answers on this site has been located! The only known photograph of the stone: The Stack Exchange Adventure Club has received word that the "All ...
0
votes
1answer
143 views

Find the missing parking space number [duplicate]

Each space in this parking area is numbered. The parked car covers one of the numbers. What is the number? For reference, the parking numbers are $16,06,68,88,X,98$ where $X$ is the hidden number.
2
votes
3answers
2k views

Should I take the antidote? [closed]

A new disease has been discovered in the world, it is called Blue. Statistically 1:1000 people in the world has it and it makes your whole skin blue in a few weeks after getting the disease but not ...
7
votes
1answer
236 views

Hiker’s Cabin Mystery | Pt. V

Be sure to see the previous parts and solve Part II because that’s the only one without an answer! After you’ve unlocked the mystery of the map, you go to (Solution to Part IV) to try and find this ...
-7
votes
2answers
184 views

The Guys - Logic #3 - The Casino

Oh boy, the guys went to the casino.. Let's see what these three are up to tonight. I wonder if going to the casino was a good idea?? Maybe for a couple of them. Start the two minute timer... The ...
-5
votes
1answer
111 views

The Guys - Logic #2 : Ways to work

So the guys are back. This time, they decide to change up their way to work. Let's see what they're up to... Start the two minute timer... 1. Since Anthony and Charles weren't taking the bus today, ...
-2
votes
1answer
169 views

The Guys - Logic #1 - Comics

Welcome to the first in a series of quick logic puzzles. The stories behind the puzzles follow 3 guys who are life long friends, went to school together, and now work in the IT field together in Tampa....
6
votes
2answers
250 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 ...
2
votes
2answers
114 views

Find the set of letters corresponding to a set of words

Each word in the following list corresponds to one letter: rôle résumé Jalapeño xoriço ö führer The combination of letters can be represented as ----uu Here, the -'s represent the missing letters. ...
5
votes
1answer
269 views

Hiker’s Cabin Mystery | Pt. IV

You’ve gotten into his computer and opened the correct file. Ready to read? The file turned out to be an image... of a map. Where is our mystery hiker hiding out and how do you know?
6
votes
1answer
138 views

Find the immediate square dancing neighbors, they dance together to perfect square

We live in a community of houses sequentially numbered from 1 to 100. We all love square dancing but only two immediate neighbors are joy to watch. If you concatenate their house numbers, it forms a ...