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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11
votes
1answer
310 views

When you stop at the top of a Ferris wheel

This is a Palisade (or Ten-Cells) puzzle. The rules are: Thicken some of the squares' sides so the thick borders outline cells of ten squares apiece. Any square with a number in it indicates how many ...
-2
votes
0answers
46 views

How many times they should journey? [closed]

In a Colony, there are men, women and children. 4 women can carry as much as water as 7 children. 3 men can carry as much as 2 women and 1 child combined. If 7 men, 15 women and 4 children each visit ...
6
votes
2answers
177 views

Can you find and capture a shapeshifter?

A town was invaded by aliens, and some of its residents were kidnapped and replaced by shapeshifters. You're tasked with capturing one of the shapeshifters. Here's the setup: There are 7 residents of ...
-5
votes
0answers
42 views

Mathematics based question [duplicate]

Vani meam has three Tatva books, one for chemistry, physics and biology. The chemistry book had 120 pages, the physics book has 10% more pages and the biology book has 10% fewer pages. In a class, she ...
12
votes
1answer
387 views

Windmill: A Masyu Puzzle

The standard Masyu rules apply.
-6
votes
0answers
82 views

Difficult question .. Plzzzz solve this question [closed]

It's question image plzz answer this question Very difficult question
1
vote
0answers
44 views

Grids with tiles of two colors and connectors

Make a square grid with an even side. Make a continuous trail which passes through all small squares; the trail ends where it started. Where there is an angle you can put a red or a blue tile. On ...
0
votes
1answer
55 views

How to solve the attached sudoku?

Please explain the logic. I am not trying to solve it using trial and error or using any software. I am just looking for the next step. This sudoku is from apple 'Sudoku King' app.
-4
votes
0answers
38 views

Rickey Rat puzzle [duplicate]

A powerful sorcerer has hired Rickey Rat as an intern. The wizard gives Rick the task of carrying water from a well to the garden. The path from the well to the garden is up a staircase with 1000 ...
2
votes
1answer
136 views

How could I solve the attached Sudoku?

Please explain the logic. I am not trying to solve it using trial and error or using any software. I am just looking for the next step. This sudoku is from apple 'Sudoku King' app.
1
vote
1answer
120 views

What is the greatest number of pencils that you cannot buy? [duplicate]

A shop sells pencils in boxes of 31 and 38. What’s the highest number of pencils a person cannot buy? In general, if the shop is selling pencils in boxes of p and q, then what is the highest number ...
9
votes
1answer
910 views

My grandfather's coins

When my grandfather died, he left his fine collection of coins, not more than 2500 of them, to his children, a different number to each of them, and in decreasing amounts according to their ages. To ...
8
votes
0answers
147 views

9x9 Sudoku Slitherlink Hybrid

I previously created a combined slitherlink and sukoku puzzle, but I was unsatisfied because the grid was smaller then a regular sudoku. So I made another, larger one. Below is a 9 by 9 grid. This is ...
13
votes
3answers
2k views

What is the age of the old man?

In autumn of the year 2003 an old man was asked about his age. He answered: "I was born on a Sunday morning in summer and I celebrated my seventh birthday on a Sunday morning too!" How old ...
9
votes
1answer
127 views

Sudoku: Episode 64 - Attack of the Clones

An 8x8 Sudoku where you technically only have to figure out 32 cells! Twice Half the cells, double the clues! Penpa Link Rules Normal Sudoku rules apply. Values are 1-8. Boxes are the 4x2 regions ...
16
votes
2answers
511 views

Pipes Puzzle Uniqueness

In the puzzle game Pipes, a space-filling tree of pipes (which may have either one, two, or three neighboring connections each, but not four) is scrambled by a series of tile rotations, and the goal ...
1
vote
2answers
158 views

To Mock a Mockingbird: 4 brothers

On page 30 of Raymond Smullyan's book To Mock a Mockingbird, we are told that there are four brothers, indistinguishable in appearance, of which Arthur is an accurate truth-teller, Bernard is an ...
6
votes
1answer
195 views

A 3x3 grid with common factors

A $3 \times 3$ grid $G$ is filled with every number from the set $\{2,3,5,6,7,11,14,15,30\}$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that ...
11
votes
4answers
914 views

Deriving a 3x3 grid from another one

A $3 \times 3$ grid $G$ is filled with every number from $1$ to $9$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that are greater than $G_{ij}$....
-1
votes
1answer
152 views

How to create a logic grid given three categories?

How do they make the three category setup here? I do not understand how this works. A detailed answer to this is most welcome.
6
votes
2answers
616 views

Reasoning puzzle involving five friends and five departments

Five friends A, B, C, D, and E are working in 5 different departments M, N, O, P and Q and they earn different salaries i.e. 10,000, 15,000, 20,000, 25,000 and 30,000 and they all are of different ...
5
votes
1answer
116 views

Sudoku + Slitherlink

I like combinations of puzzles, so I decided to combine a Sudoku and a Slitherlink. Below is a 6 by 6 grid. This is filled in with numbers based on the usual rules of sudoku. All of the numbers from 1 ...
-1
votes
1answer
111 views

Fillomino: Number Attack!

This is my first time making a Fillomino. Hope you enjoy! Fillomino (taken from Nikoli): Fill in all empty cells with numbers under the following rules. Divide all of the board into blocks. Fill ...
9
votes
1answer
474 views

Plants vs Zombies!

Several plants and zombies (no more than 20 creatures in total) came to the party “Plants VS Zombies”, and it turned out that all the creatures are of different heights. When a plant speaks to a lower ...
8
votes
5answers
1k views

Split 1 through 6 into a product of 24 and sum of 12

How many ways are there to split the numbers 1, 2, 3, 4, 5, and 6 into two groups, such that the product of the numbers in one group is 24 and the sum of the numbers in the other group is 12? An ...
21
votes
1answer
518 views

Slitherlink: Around the W0rld

Rules of Slitherlink: Connect adjacent dots with vertical or horizontal lines to make a single loop. The numbers indicate how many lines surround it, while empty cells may be surrounded by any number ...
3
votes
1answer
152 views

9 people sitting at a round table

I am unable to figure out how to solve this question @Joffan has given an answer but he hasn't mentioned much regarding his approach. I requested him but he still didn't give a clear answer. This is ...
-1
votes
1answer
121 views

Skyscrapers 7x7 How to get next Skyscraper on field

I have the following Skyscrapers puzzle: C3 C1 C2 C3 C4 C4 C2 C2 V3 C5 C4 V1 C1 C3 C4 C2 V5 C3 C3 V7 C3 C3 V4 V2 C2 C1 V2 C2 C1 C3 C4 C2 C2 C2 C2 C -> Clues how many ...
10
votes
3answers
879 views

Calculation Sudoku

Here is a new quiz from my daily quiz calendar. I'm trying to find a way to solve it. The numbers 1-6 should be filled in. And like a sudoku, each row and each column should contain each number ...
18
votes
1answer
370 views

A constrained, but concerning, celestial confrontation

An entry in Fortnightly Topic Challenge #52: Polyominoes. This puzzle is a hybrid between Pentominous and Star Battle. Your job is to divide the grid below into pentominoes according to the rules of ...
1
vote
1answer
105 views

Next Move on this Sudoku Classic

What would be the next move? Link to this sudoku
15
votes
7answers
2k views

Flashlight and 8 batteries

A flashlight requires 2 AA-type batteries to operate. Both these batteries need to be charged for the flashlight to provide light. We happen to have 8 batteries, but 4 of them are charged while the ...
3
votes
1answer
182 views

3 weird images from a friend

I got sent this from a year ago, and I am still thinking what was the secret number that they hid a secret from, so here are the pictures. The first one was a car, and a random equation. The next one ...
4
votes
1answer
247 views

Trapped in an escape room with 2 liars

You are in a room, with 6 people. 2 of them are liars. The room has a code pad. The people say: People What they say Keith The first and last digit are the same number and are not used anywhere else ...
4
votes
3answers
781 views

Why is the next Sudoku step a 6?

I used a step-by-step Sudoku solver for a puzzle in which I was stuck. However I don't understand how the next number (6) was found. Sudoku puzzle where I was stuck: Sudoku puzzle solved by one step ...
1
vote
1answer
90 views

4-DominoBrane #002 “81”

Here is another domino puzzle. This is considerably easier than puzzle set earlier this week, and definitely doesn’t need bifurcation. This uses 4-Dominoes (all the normal dominoes, minus any with a 5 ...
13
votes
1answer
283 views

Tapa on a Penrose Tiling

An entry in Fortnightly Topic Challenge #51: Non-rectangular grids. This is a standard Tapa puzzle, on a non-standard Tapa grid...the "grid" is a Penrose tiling! Since the grid is not ...
3
votes
1answer
226 views

Slitherlink: The Couple of Question Marks

This is my first slitherlink puzzle. I made it myself. Feedback is appreciated! (I hope this one has a unique solution, unlike my other past puzzles, wink). Rules of Slitherlink (taken from Nikoli): ...
1
vote
1answer
122 views

4-DominoBrane Exclusive

Here is a smaller puzzle from the set of domino puzzles, I call DominoBrane. This uses 4-Dominoes (all the normal dominoes, minus any with a 5 or a 6). Each domino ...
4
votes
1answer
152 views

DominoBrane - Chained Domino Fitting

So I've been working on a set of domino puzzles, I call DominoBrane recently, it's sort of similar to Dominosa - except that, unlike Dominosa, the rules of the ...
15
votes
1answer
294 views

Haisu: Schezo's Birthday

Rules of Haisu: Draw a path from S to G passing through all white cells exactly once by connecting the centres of adjacent cells. When the path passes over a number N, it is on its N-th entry to the ...
2
votes
1answer
256 views

Arrange candies without repeating pattern

The following puzzle had been posted before but I couldn't understand the only answer that was given there, which was by @neodne . So, I created this post asking someone to explain neodne's answer to ...
3
votes
1answer
147 views

Swapping eggs puzzle

You can try this with pencil and paper, or make it a physical puzzle you can try out with your kids if you have one of those large 3x6 egg cartons laying around. Imagine you have 3 rows of 6 spots. ...
10
votes
1answer
289 views

The Nurikabe of Peace

Today is the 75th anniversary of Sir Winston Churchill's speech "The Sinews of Peace" which introduced to the world the phrase "The Iron Curtain". This puzzle is inspired by that ...
7
votes
4answers
761 views

Sorting 6 boxes by selecting 3 boxes each time

There are 6 boxes, each containing a distinct number. You can select 3 boxes and the Oracle will tell you which box has the smallest number and which has the largest number of the three selected boxes....
8
votes
2answers
212 views

Double sudoku - two-digit numbers, the 1s and 10s places both form Sudokus [closed]

Using distinct 2-digit numbers from 11-99 that have no zeros, fill in the grid so that the tens digits form a Sudoku and the units digits form a (different) Sudoku. There might be a mathematical way ...
1
vote
5answers
194 views

Another (simple) self-referential aptitude test

Nine months ago I started my journey on Puzzling in a rough way with this question. I honesty hope this time I won't generate so extended discussion...! I love self-referential questions, puzzles or ...
19
votes
1answer
403 views

Escape from Sudoku!

An entry in Fortnightly Topic Challenge #50: Escape Rooms I hesitated to enter this in the Escape Room FTC, but I definitely was inspired by the challenge to create this puzzle, and it is, in some ...
1
vote
4answers
150 views

I need some help with this 15x15 nonogram

I have been working on this nonogram for some time and can't seen to figure out what to do next... This is the link: https://nonograms-katana.com/play/#game
5
votes
1answer
229 views

How to get the least possible sum in a closed loop set of squares?

The puzzle is as follows: The figure from below represents a set of 12 squares joined forming a closed loop. By using only the numbers from 1 to 12 fill in the blanks. The condition is that, without ...

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