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
0 answers
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its an image based question the answer can or cannot be a part of the image [closed]

We've tried all the obvious answers like their names, personality, what they do, how many cars they've crashed and what company they've worked for.
sheeeeeeeeeeeeeshhhhhhhhh's user avatar
13 votes
1 answer
602 views

Colourful Scenery

This is part 41 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a Word Nurikabe puzzle. Shade some cells in the grid. Shaded cells must ...
Jafe's user avatar
  • 75.6k
18 votes
1 answer
962 views

A Trivial Pursuit #12 (Sports and Leisure 2/4): Logic Boat

This is part 12 of A Trivial Pursuit, a 25-part puzzle hunt. Each part is solvable on its own, with the exception of the meta-puzzle at the end. This is a variation on a Battleships puzzle, where the ...
Stiv's user avatar
  • 129k
1 vote
2 answers
204 views

Logic and Geometry Problem #5: does Savage Go have cycles?

My question is whether or not a cycle can occur in the game of Savage Go. That is, you kill some of mine, I kill some of yours, you kill some of mine... Endless cycle of turns. Game never finishes. No ...
Mark Steere's user avatar
15 votes
2 answers
1k views

Very small regional Yajilin

This puzzle is part of the Monthly Topic Challenge #14: Think inside the (very small) box!. Rules of regional Yajilin: Shade some cells in the grid. Two shaded cells cannot share an edge, but can ...
Jafe's user avatar
  • 75.6k
4 votes
1 answer
310 views

Nonogram with story

Fellow puzzlers, here's a nonogram I made for you. But it also has a story! Two bored male casino dealers are waiting at the craps table. A very attractive blond woman arrives and bets $20,000 on a ...
cdm's user avatar
  • 221
4 votes
0 answers
101 views

Continue the squence of hexagons

This is from c't, a German IT magazine (link will download file). You see seven hexagons, each with seven green and blue dots, following a specific rule. Find out what colors the circles must have to ...
Mighty4711's user avatar
3 votes
1 answer
239 views

Justifying a redouble

This puzzle is derived from a real game of bridge I played on Bridge Base Online. I was sitting North on board 9 (N dealer, E-W vulnerable) and the bidding turned out like this: West North East South ...
Parcly Taxel's user avatar
  • 6,954
0 votes
1 answer
151 views

A Problem in Research using Logic

Here's a problem of my own design. You are researching 5 papers done in your field in order to guide your next paper. Some papers may have had a bad study design, used faked data, or otherwise would ...
Bob Bixler's user avatar
3 votes
2 answers
346 views

“Pickled Walnuts” Logic Problem

Here's a problem by puzzle composer Hubert Phillips called “Pickled Walnuts”. What conclusions (if any) can be drawn about armadillos and picked walnuts, assuming all statements are true? Pickled ...
Bob Bixler's user avatar
1 vote
1 answer
217 views

What was the date of Michael's birth?

Michael was so obsessed with his birthday that he always held his birthday party on the exact date and time of his birth. But he didn't hold his birthday for 8 years (he held his 16th birthday and ...
Etack Sxchange's user avatar
-2 votes
1 answer
153 views

What are the largest and smallest numbers in decimal base in this special Sudoku?

I have constructed the following hexadecimal 16×16 sudoku in this site: The rules are like 9×9 sudoku tables (each number and letter should repeat only one time in each column, row, and 4×4 ...
Etack Sxchange's user avatar
7 votes
5 answers
487 views

Mexican Standoff -- 4 way

You and 3 others are being held captive by the Great Leader and will be forced to engage in a 4-way shootout. The last one standing will be set free and the top priority for all involved is to go ...
Bob Bixler's user avatar
4 votes
1 answer
188 views

Find unique values for the variables to make all statements true

In this puzzle you have to find unique values for the variables to make all statements true. I have proceeded to here and now I seem to be stuck.
Teodor Dyakov's user avatar
8 votes
1 answer
372 views

gambas al ajillo

This is a Tapa puzzle. That means you must shade some of the squares, so that: No square containing text is shaded. Numbers in a square indicate runs of consecutive shaded squares among the ≤eight ...
msh210's user avatar
  • 11.6k
-3 votes
0 answers
168 views

You need to unfold the given figure

Unfold the given shape and find the answer Source: UCEED (entrance exam for design colleges in India) The given answer is B. I don't understand why this is the answer; how can I approach this kind of ...
Sumeet Redhu's user avatar
3 votes
3 answers
301 views

Logic and geometry problem #4: are these games functionality equivalent?

Two games, Crossway and Mincut, are believed to be functionally equivalent. That is, a win by Crossway rules will necessarily lead to a win by Mincut rules. And a win in Mincut will be a win in ...
Mark Steere's user avatar
-4 votes
1 answer
161 views

Find the Rat in the Hole

A rat is in one of 100 holes that are in a line. Each night he moves to the left or right 0,1, or 2 holes randomly selected. You pick one hole each day to look in until you find him. What procedure ...
Bob Bixler's user avatar
15 votes
1 answer
329 views

Slither-Yajilink: A match made in Hades

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. This is a Slitherlink-Yajilin hybrid. Shade some cells in the grid and draw one non-crossing, non-branching line ...
Jafe's user avatar
  • 75.6k
3 votes
3 answers
778 views

Was Humpty Dumpty right?

Raymond Smullyan's What is the Name of This Book? contains a puzzle which I'll paraphrase here: Of the identical twins Tweedledum and Tweedledee, one of them lies on Mondays, Tuesdays and Wednesdays ...
fblundun's user avatar
  • 932
6 votes
3 answers
322 views

Zodiac Signs at the Table

"And we find ourselves at another one of Ophiuchus' little themed puzzle dinners," you say while glancing at the other seven people. "I really like its puzzle dinners, honestly," ...
CatProgrammer's user avatar
15 votes
1 answer
420 views

Seven similar 7x7 (pen-and-paper) logic puzzles

Oh no! I've just finished drafting some 7x7 logic puzzles, but I accidentally dropped all of them on the floor, and now they're all mixed up! To make matters worse, I haven't gotten around to ...
Kusane Hexaku's user avatar
7 votes
1 answer
307 views

A Watery Slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. A watermill is going to be built next to a cozy town. You are the designer of the aforementioned mill/slitherlink, and ...
new Q Open Wid's user avatar
8 votes
1 answer
313 views

Alice knows a+b, Bob knows a×b. Can we find (a,b)?

There are two distinct positive integers $a,b$ (i.e. $a\neq b$) such that $a < 7$ and $b < 7$. Alice has been told the sum of $a$ and $b$. Bob has been told the product of $a$ and $b$. Both ...
Hemant Agarwal's user avatar
2 votes
1 answer
156 views

Logic and geometry problem #3: are cycles possible in Scattercut with added "maximum" rule?

My question is whether or not cycles can occur in the game of Scattercut. That is, you kill some of mine, I kill some of yours, you kill some of mine... Endless cycle of turns. Game never finishes. ...
Mark Steere's user avatar
-6 votes
1 answer
174 views

Beauty, chef and boxer

Sarah, Megan, and Mike all attended a party last night. Sarah is a beauty pageant winner, Megan is a chef, and Mike is a boxer. The host of the party said that one person told a lie during the evening,...
Uk rain troll's user avatar
0 votes
0 answers
73 views

Find the largest number with unique digits, that is divisible by each of its digits [duplicate]

Find the largest number with unique digits, that is divisible by each of its digits. For example 132 has unique digits and is divisible by 1, 2 and 3. But it is not the largest such number. Can you ...
Teodor Dyakov's user avatar
2 votes
0 answers
94 views

Assemble n^3 cubes into n different n×n×n larger cubes [duplicate]

You might have seen this question before: Goal: Paint 27 cubes using three colors (for example, red, yellow, and blue), so that you can form a 3x3x3 cube with all surfaces in red (for example), a ...
Haspamelodica's user avatar
13 votes
1 answer
349 views

Nurikabe: Forties

The good news: It’s my birthday! The bad news: I’m 40 now. It’s not a great update. Just weaker stats with no cool new abilities. Anyway, here’s a Nurikabe to celebrate. Don’t worry, it should be good ...
Jafe's user avatar
  • 75.6k
14 votes
1 answer
340 views

Double trouble - When slitherloops collide

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. What happens when you're working on a couple of puzzles for the Monthly Topic Challenge and try to merge them? Well, in ...
fljx's user avatar
  • 12.9k
10 votes
1 answer
300 views

Walking a twisted path on a donut - a Möbius Slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Have you ever wondered why there has to be an "inside" and an "outside" to every slitherlink loop? ...
fljx's user avatar
  • 12.9k
14 votes
1 answer
754 views

Slither-Numberlink: A monstrosity nature never intended

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Rules of hexagonal Slither-Numberlink: Some numbers in the grid are slitherlink clues, some are numberlink clues. Zeroes ...
Jafe's user avatar
  • 75.6k
5 votes
1 answer
392 views

Counting Tic-Tac-Toe draws on larger grids

Alice and Bob play a game of Tic-Tac-Toe on a grid of size $N \times M$. The rules of this game are the same as the original Tic-Tac-Toe: Alice plays first (white); Bob plays second (black). On each ...
Bubbler's user avatar
  • 11.5k
16 votes
1 answer
655 views

SlitherLITS: Don't colour outside the lines

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Adding a bit of colour to enhance the loopy goodness of a traditional Slitherlink. Draw a single, non-intersecting loop ...
fljx's user avatar
  • 12.9k
2 votes
1 answer
260 views

How to solve large "crack the lock" questions

I already have the solution for this crack the lock puzzle but am stuck on how to get there. The smaller puzzles I've solved use a different style of deductive reasoning. Rules: For this specific ...
Rcyr1010's user avatar
  • 129
5 votes
0 answers
204 views

Next Sudoku Number

Here is a sudoku puzzle coming from this magazine I found that B5 and B6 can only contain 6 and 7. 8 cannot be in B5 because D1 would be a 8 and neither B3 not C1 could be a 8. I thought it would help ...
Olivier Boissé's user avatar
17 votes
1 answer
950 views

An oddly coloured slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. I find something strangely satisfying about a well designed slitherlink puzzle, even one which is oddly coloured and ...
fljx's user avatar
  • 12.9k
27 votes
3 answers
4k views

If A cents can be paid with B coins then prove that B dollars can be paid with A coins

Looking for an intuitive solution to the following problem: In a certain country the following coins are in circulation: 1 cent, 2 cents, 5 cents, 10 cents, 20 cents, 50 cents, and 1 dollar. It is ...
Hemant Agarwal's user avatar
7 votes
0 answers
144 views

Logic and geometry problem 2

My question is whether or not a deadlock can occur in Crisscross. A deadlock is defined as a position, an arrangement of checkers, in which the board has been filled but neither player has won. ...
Mark Steere's user avatar
22 votes
1 answer
961 views

The Metaslitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Below is a grid containing multiple small slitherlinks. These can be independently solved to form clues for the large ...
sarsaparilla's user avatar
  • 5,006
2 votes
1 answer
366 views

Sheets of paper on foreheads in a quiz show [duplicate]

I have got a puzzle that I wanted to share. In a quiz show, three candidates were shown five slips of paper - three white and two black. Then they were blindfolded and one of the slips of paper was ...
calculatormathematical's user avatar
3 votes
2 answers
333 views

Lightbulbs in Two Separate Rooms

You are in a room with six light switches. Down the hallway, there are two other rooms, each with three incandescent lightbulbs. Each lightbulb is uniquely controlled by exactly one of the switches. ...
mintmocha's user avatar
  • 175
0 votes
0 answers
154 views

Logic puzzles: Flags and Stripes

Puzzle 1 Puzzle 2 Clues The only instructions given to solve this is that the answer can be alpha-numeric text. Ideas Puzzle 1: 3 flagpoles seem to have top-balls (called a truck), while 3 don't ...
nomad.lw's user avatar
5 votes
0 answers
208 views

Shape puzzle, find the final sequesnce or word? [closed]

Clues: The only instructions given to solve this is that the answer can be alpha-numeric text. Ideas: So far I have this: SQUARE: 101111 DIAMOND: 2111112 RECTANGLE: 111211021 HEXAGON: ?1?1011 Though ...
nomad.lw's user avatar
0 votes
0 answers
177 views

Puzzle Challenge: Unraveling the the Circular Conundrum

Known are five numbers: 1, 2, 3, 4, and 5, arranged clockwise. The number after 1 is 2, after 2 is 3, after 3 is 4, after 4 is 5, and after 5 is 1. Whenever two adjacent numbers meet, it triggers a ...
Kevin's user avatar
  • 1
7 votes
1 answer
372 views

Logic and geometry problem

My question is whether or not cycles can occur in the abstract game, Clearcut. Clearcut A few smart guys (and me) have been trying to either find a cycle or prove that one can't happen. Ten days ...
Mark Steere's user avatar
6 votes
1 answer
284 views

Is the Parity Sudoku solvable?

I have a new kind of grid puzzle (you could call it a variant of sudoku) I will be calling a Parity Sudoku. Parity Sudoku is played on a 6x6 grid of integer cells with numbers ranging from 1 to 6. It ...
new Q Open Wid's user avatar
2 votes
1 answer
385 views

How is the tree colored?

Not relevant fiction context Paul's journey in the mathematical forest began this early morning. You know, he is a Biomathologist! He saw a lot of spectacular plants, geometrical flowers and fractal ...
10010100102ohno's user avatar
-4 votes
2 answers
135 views

If ABCDE*4 = EDCBA. A,B,C,D and E are all natural numbers ( 1-9) without repeating any natural number. Why is it deducible that E cannot be three?

If ABCDE*4 = EDCBA. ABCDE,EDCBA are five digit numbers. A,B,C,D and E are all natural numbers ( 1-9) without repeating any natural number. Why is it deducible that E cannot be three?
jkj's user avatar
  • 21
9 votes
4 answers
2k views

Where to start with a large crack the lock puzzle like this?

Below is a puzzle called crack the lock. The rules are simple: the lock contains 16 characters in this particular puzzle No character can be used twice the two numbers on the the far right tell you ...
Rcyr1010's user avatar
  • 129

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