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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5
votes
3answers
350 views

Shocks and guesses

The Liar, the Random and Truth teller were captured and brainwashed to forget whether they always lie or tell truth or randomly answer.Everyone is handcuffed to a chair and gagged with gray, white and ...
9
votes
2answers
950 views

Sudoku Help: Hard

I am unable to finish this Sudoku. All numbers are verified by the app. I'm sure there must be a way to solve this without guessing. Even an online tool couldn't tell me a next number.
9
votes
1answer
245 views

Simon Tatham's Gokigen Naname

Lately, I've been interested in Gokigen Naname a.k.a Slalom a.k.a Slant. Luckily, Simon Tatham has a generator for Slant. Usually, the generated puzzle is so-so, but this particular generated puzzle ...
4
votes
4answers
984 views

Give me a clue!

Create a Nonogram / Picross which cannot be solved uniquely without giving at least one clue. That is, without prefilling at least one field in the puzzle there exists multiple valid solutions. The ...
9
votes
1answer
683 views

Weird and complex puzzle that we need help with

So basically this is a complex deep web puzzle and we're pretty much stuck at it right now as we don't have any idea what this is about, any help will be aprreciated (the attached images are the ...
1
vote
5answers
218 views

A couple have 9 children, half of children are boys, how? [closed]

My friend asked me the puzzle, A couple have 9 children (none of them were adopted) Each child must be either a boy or a girl Half of that couple’s children are boys How that can be ...
19
votes
2answers
967 views

Tic tac toe - Sudoku: A variation in which the centre box defines the layout of the other boxes

I stumbled across this interesting variation of Sudoku the other day and thought I'd give it a try, it has however baffled me and I've been unable to progress past the very early stages. The puzzle ...
6
votes
1answer
225 views

Logic puzzle about six college freshmen

I found some logic puzzles on someone's blog from a few years ago, and have been trying to solve them. Here's the link to the page: https://hedgehogcomms.blogspot.com/2015/04/puzzling-over-logic-...
-10
votes
1answer
117 views

N-1 queen on the chessboard

You are trying to solve the famous N queens problem. You broke one of the queens from your chess pieces collections. Now, you have created the following puzzle: You are given an N*N chessboard. Is ...
2
votes
1answer
144 views

Logic grid puzzle

I found some logic puzzles on someone's blog from a few years ago, and have been trying to solve them. Here's the link to the page. Please let me know if you have any suggestions! I have looked at ...
13
votes
1answer
451 views

Tapa - Confluence

This is a Tapa puzzle. Rules of Tapa: Shade some cells of the grid. Shaded cells should form a single [orthogonally] connected group; no 2×2 square should be fully shaded. Some cells have ...
14
votes
8answers
4k views

How to get 32 by using +1 , +1 , ×3 , ×3 , ÷2 , ÷2, ^2, ^2?

How to get 32 by using +1,+1,×3,×3,÷2,÷2,^2,^2? (The last two operators are 'squaring'.)
5
votes
1answer
194 views

Shingoki: Choices

This is a Shingoki puzzle. The goal is to make a single loop in the grid which satisfies the following rules.1 The line passes through dots and numbers in the grid, vertically and horizontally, ...
8
votes
2answers
296 views

Have you heard Gokigen Naname?

Here is a regular Gokigen Naname a.k.a Slalom a.k.a Slant puzzle. An online (mobile-friendly) version is available here. Rules: Put a slash (diagonal line) on each cell. Each number ...
62
votes
15answers
20k 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, ...
1
vote
0answers
116 views

What number should be on the questionmark? [closed]

Please explain your answer below
8
votes
4answers
998 views

Find the missing number in this transformation

I've recently come accross this puzzle. 2,5,8 = 122348 3,5,4 = 181224 7,4,6 = 352230 5,3,10 = 203340 3,9,4 = ? I was able to figure out 30**40 but couldn't ...
3
votes
1answer
129 views

4 balls and a balance scale

What's the least amount of weighings you'd need to be able to successfully determine the weights of 4 balls weighing 1, 2, 3 and 4 kilograms, using a balance scale (counting the worst scenario)? Any ...
9
votes
1answer
187 views
0
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1answer
134 views

Math tapestry puzzle #2

This continues from Math tapestry puzzle #1. Find the rules there. Continuing on from that, I saw my friend Jason come outside. We had a conversation about the things that are here. Suddenly he says: ...
2
votes
1answer
93 views

Next move for Sudoku puzzle

I am currently stuck at this point in the below Sudoku puzzle. What is my next move and why? Thanks!
2
votes
2answers
177 views

Puzzle of 26 brothers

Of all the 26 brothers, I am the first son. With me it starts, the biggest one You know it, the chance to not know is least Of all the places in the world It’s fav hangout is Middle East
2
votes
2answers
430 views

Puzzle of the day

The aim is to draw a single contiguous line from the upper left corner to the lower right corner. The line includes each number from 1 to 39 exactly once. CSV: 1,25,23,12,31, 3,20, 2,15,13,19,23 36,...
3
votes
3answers
2k views

“Guess the number” game

two logicians decided to play a lovely well-known game , number-guessing from the least significant informations , the juror proposed to create the challenge : the juror told the logicians two ...
7
votes
2answers
279 views

Algorithm for creating a “Dot” logic maze

I've been looking at Robert Abbott's logic mazes, in particular his Dot maze, and I'm trying to understand how they can be constructed so I can write an algorithm to do this automatically for ...
7
votes
2answers
178 views

What Goes Round (Begriddled logic puzzle)

Join adjacent numbers in the below grid to reveal the hidden content. The rules are: 1: Join all pairs of vertically and horizontally adjacent numbers that are the same. 2: Join all pairs of ...
15
votes
1answer
360 views

“Is dot a fact?”

You're presented with a five-by-five grid of dots. Each dot is assigned a label from 1 to 25 going across the rows and down. Thus, the top-left dot is number 1; the bottom-left dot is 21. Your job ...
9
votes
2answers
444 views

Can you solve this grid?

I'm not completely sure there is enough information here to solve these puzzles, if not I'll add hints until someone solves it. Rules: The numbers $1$ to $12$ appear once each. The numbers on the ...
2
votes
2answers
223 views

Logical Sudoku - How to tell when fully deducted?

I'm working a program that should generate bad ass sudoku puzzles. Recently I noticed there's a thing called "logical sudoku", which means it can be logical-deducted all the way to solution. The ...
1
vote
1answer
139 views

What is the solution to this Raven-Style Matrix Question

I'm stuck on this one. Which one do you all think it is? Source: http://www.vuksfrj.se/zabava/IQ%20test/testinteligencije.html
6
votes
1answer
399 views

What are my five numbers?

This nice puzzle was sent to me by a friend. I don't have the original source. I am thinking of 5 numbers A, B, C, D, E, in that order. Each number is a unique digit between 1 and 9. 79314 contains ...
4
votes
2answers
311 views

The Genius Bank Robber

StackVille Bank & Trust - Robbed! The Robbery The bank is being robbed. There are millions in cash in the vault. The lone robber takes the manager to the safe and demands he opens it. The manager ...
9
votes
1answer
287 views

Pizza and Subs - Delivery Dilemma

The Delivery Dilemma The local pizza joint delivered pizza and subs. Three employees were hired to deliver: John, Heather, and Luigi. Based on the following statements: If John delivered pizza, then ...
5
votes
2answers
516 views

I'm stuck on this game of Slitherlink

I'm stuck on this game of Slitherlink. What deduction (or deductions) can be made from here? Am I missing something obvious? I verified that everything I have so far is correct by looking at the ...
19
votes
4answers
3k views

After here should I guess or is there a logic solution on Sudoku?

From this point is it necessary to guess or is it possible to find a logic solution?
13
votes
3answers
3k views

Show this man the exit, enter into cell only once and should cover all cells

Show this man the exit Conditions : should cover all cells should not enter the cell twice (only once)
7
votes
2answers
229 views

Puzzle of the day, Frame Sudoku

The rules are the same as the classic Sudoku, but the numbers outside the grid are the sum of the first three digits placed closest to that row or column
9
votes
3answers
2k views

Can somebody answer this 'Crack the code'?

Can somebody answer this? It was given to me as a challenge and I am having doubts in my answer Text version: 2 6 5 7 - Has two correct digits but neither are in the correct place 0 4 1 5 - Has ...
11
votes
1answer
305 views

Introducing: MIXXOX Grid Puzzle!

Rules of MIXXOX: Put either X or O in each empty cell. A border between two adjacent cells may have a mirror, denoted by a bold line. Some mirrors are already given. Note that the outer ...
7
votes
1answer
283 views

Prisoner Released If ? ??

One day a prison guard noticed a series of numbers scratched on the wall of an inmate's cell. Concerned it was something to do with an escape plan, the inmate was immediately questioned. 0-2-0-4-0-0-0-...
-1
votes
1answer
110 views

The Team Roster Mystery

Game Day When the managers of the Tampa Times and St. Pete Sun met for their annual company baseball game, everyone decided by unanimous vote that they wanted a different method of choosing which team ...
7
votes
1answer
214 views

Nurikabe: Build it yourself

This is a Nurikabe puzzle. First form a 16 × 16 grid using the provided squares, then solve the grid by shading some cells so that the resulting grid satisfies the rules1 of Nurikabe: Numbered cells ...
15
votes
1answer
403 views

Kropki Sudoku – Sudoku based on the relation between neighbouring numbers

This puzzle is named Kropki Sudoku. The classic sudoku rules apply: Place numbers on the grid below such that each row, column and 3×3 box contain the numbers 1 to 9. A white dot indicates that the ...
1
vote
2answers
131 views

What's the gorilla's address?

There's four houses next to each other, somewhere in suburb Netopia. Johnny lives in number 3. The red house is in between the white and yellow houses. Mickey does not live at the end. House number 9 ...
0
votes
1answer
129 views

The Coding Contest

A coding competition in Netopia pitted each PHP Programmer contestant against every VB Programmer and C++ Programmer contestant, each VB Programmer contestant against every PHP and C++ contestant, ...
1
vote
1answer
118 views

The Thrilling Chase

Our story takes place in the future. Earth has been invaded by an evil alien species, known by the humans as simply, "The Bots". They are essentially robots, but sophisticated and evil. ...
3
votes
1answer
169 views

The puzzle of the day

This is called Hidato or Snake Puzzle ! The goal of Hidato is to fill the grid with consecutive numbers that connect horizontally, vertically, or diagonally. For your help, the grid is already filled ...
2
votes
1answer
99 views

The Magic LeaderBoard

Every Saturday at Netopia's Square, a peninsula at the tip of southwest Netopia, there is a leaderboard kept of Netopia's Square's six local resident wizards. (in no particular order) They are ranked ...
4
votes
2answers
160 views

Solving an alphametic puzzle by eavesdropping

I took part in a meeting of puzzle maniacs. I overheard a conversation between two persons. A: Hey, solve this alphametic problem. LHS is a square of two-digit number and RHS is a four-digit number. ...
4
votes
1answer
224 views

Old Ladies Day Out

During this unfortunate Corona situation in Stackville the WalMart is closed every Monday, BestBUY is closed every Tuesday, the Liquor Store is closed every Thursday, and the bank is open only on ...

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