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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2
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2answers
90 views

Mario's Super Picross - Stage Mario 9-K

I'm playing through Mario's Super Picross currently and after nearly 200 puzzles this one finally has me stumped as to how it is intended to be solved. What is the next step to solving this? Notes: ...
14
votes
1answer
310 views

Cartological Cats: A Snaky-Loop Grid Puzzle with Cat-Shaped Matchmaking Clues

This is written for calica for a Secret Santa puzzle exchange. The original version in a printable PDF format can be found here. Dear calica, Thank you so much for being an amazing person this year! ...
5
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2answers
155 views

How many coins did Raj get?

I found a bunch of coins: Quarters (25 cents), Dimes(10 cents) and Nickels(5 cents). The combined amount was a whole two digit number of dollars: that is, no fractional amount. I divided the coins ...
2
votes
1answer
219 views

Prove the existence of a triangle such that all of its sides are of the same color [closed]

Seventeen points have been picked in a plane, and each pair of points has been connected by a line segment of one of three colors: red, yellow, or green. Prove that there are three points which are ...
0
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1answer
86 views

Is X-Sudoku easier to solve than classic Sudoku [closed]

X-Sudoku has extra rule for diagonals which give extra hints for diagonal cells. Does this implies that solving X-Sudoku puzzles are easier than classic Sudoku puzzles?
4
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3answers
868 views

Finding a Kakuro trick

The following screenshot is taken from the Android app Kakuro++ (level 9 riddle 12) And I verified the current status within the app. I managed to solve the puzzle by guessing a 50/50-number and ...
-1
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0answers
165 views

Need help with an ARG puzzle

I am attempting to solve a puzzle on angusnicneven.com It contains entering things into the url to move forward https://angusnicneven.com/Terminal_230_psst I found a series of numbers on this page ...
10
votes
1answer
209 views

Snowcaps - A grid deduction puzzle

This winter-themed puzzle is basically an upside-down Aquarium, the idea being that instead of fish tanks being filled with water, the areas are mountains being covered with snow. The goal is to shade ...
1
vote
1answer
179 views

Missing rectangle

Of eight 2x4 rectangles, seven are shown below and one is missing. Which is the missing rectangle?
20
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1answer
459 views

PSE Advent Calendar 2021 (Day 24): The Witneys - Your Comfy Puzzles

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 200 reputation.< Previous Door Your great-grandmother ...
28
votes
1answer
621 views

PSE Advent Calendar 2021 (Day 20): Candy Cane Sudoku

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > So I was ...
11
votes
1answer
471 views

PSE Advent Calendar 2021 (Day 19): Santa's Dilemma

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 100 reputation.< Previous Door Next Door > It was ...
12
votes
1answer
421 views

PSE Advent Calendar 2021 (Day 17): That's the way the cookie crumbles

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > In our house,...
9
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2answers
457 views

Christmas tree LITSO

Inspired by PSE Advent Calendar 2021 (Day 13): A Christmas Hokuro, I challenged myself to create a Christmas tree-shaped puzzle. Unfortunately I had to edit the shape a little bit because... reasons. ...
15
votes
1answer
568 views

PSE Advent Calendar 2021 (Day 13): A Christmas Hokuro

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > Hokuro is a ...
0
votes
1answer
267 views

Words created by permutations of a 7-letter word in a grid

Below is a 7x7 square grid. On the top row is a single word with seven letters. From the permutation of the letters of this word, one word has been created. Is it possible to create a solution with 15 ...
7
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3answers
181 views

Place digits from 1 to 7 into each row and each column of the grid once. Numbers in the circles give the product of the four surrounding digits

What is the way to resolve the following puzzle? Link to source. It's from a taiwanese math olympiad held in 2005.
3
votes
1answer
169 views

The age of three ladies

Three ladies A, B and C have a discussion, where each lady says the truth twice and lies once. A: B is two years older than me B: C is 38 years old C: A is older than me B: The age difference between ...
11
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2answers
1k views

The missing square

From a total of 9 squares, 8 are shown below. Draw the missing square.
13
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2answers
591 views

PSE Advent Calendar 2021 (Day 4): Decorating with Ingrid Deduction

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation. < Previous Door Next Door > "...
7
votes
2answers
966 views

A rectangle cut into two pieces, which build a square

A rectangle with side length a and b are in ratio $a : b = (n+1)^2 : n^2$, where n is a positive integer. Is it possible to cut each such rectangle into two pieces, which can be put together to build ...
4
votes
2answers
483 views

How many seats around the table?

This puzzle is very much inspired by a recent, excellent, one, posted here. If anyone, in particular the author of the other puzzle, prefers this one to disappear, I will immediately do so and I ...
2
votes
1answer
136 views

Find two integers based on their sum and a random number

Alice, Bob and Charlie play a game. Alice writes down two positive integers on a blackboard visible to Bob and Charlie. She says that one of them is of her own choice, the other number is the sum of ...
5
votes
1answer
239 views

10x10 Fillomino

Interactive solving website For help/rules on solving, please look at the website's "help" section, which lists fillomino rules. Please use the website to solve the puzzle unless you are ...
-2
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1answer
165 views

Colored trominoes touching corner-to-corner on a grid

Let's have an 8x8 GRID to be filled with L-trominoes of 3 different colors. 64 squares leave room for 21 trominoes, so there should be 7 trominoes of each color and one empty square. Trominoes of the ...
3
votes
1answer
327 views

How many consecutive integers to ensure one has digit sum divisible by 19?

How many consecutive positive integers are at least required, such that there is always a number in such a sequence whose sum of digits is divisible by 19?
3
votes
1answer
197 views

The Mermaids' Rooms

You have been tasked with assigning rooms to some mermaids who have visited the hotel. There are 9 mermaids: One is bald and bare-skinned One has a layer of fur One has a thick bark on their back One ...
6
votes
1answer
176 views

42 lines on a chessboard with associated numbers

The 64 squares of a chessboard can be associated with 42 lines as follows: the 8 rows the 8 columns 13 diagonals from north-west to south-east 13 diagonals from north-east to south-west Those ...
1
vote
1answer
262 views

Pokemon battle puzzle: Chansey vs Wobbuffet

This is a 1v1 battle between two pokemons: Chansey vs Wobbuffet. Your task is to analyze the battle and predict its outcome. Information about the battle: The battle takes place in Generation III. ...
16
votes
2answers
1k views

The Golden Age of Sudoku

Rules: Each cell contains one of the following symbols: A23456789TJQK. No two cells in the same row or column have the same symbol. The grid is divided into 11 square regions of different sizes. A ...
4
votes
1answer
779 views

Am I able to mark mines with the bottom row of 3's?

Am I able to use the bottom row of 3's to know what some of the squares around it are?
14
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2answers
843 views

Building equilateral triangles by reflecting tokens

Three tokens are placed at the vertices of an equilateral triangle with side length 1. A move is to reflect a token at any other token. After several moves the tokens build again an equilateral ...
2
votes
1answer
282 views

Two people buying gingerbread and gluehwein in an efficient way [closed]

Bud and Terence visit a Christmas Market. Bud checks his money and notes that he could buy 8 gingerbread and 1 gluehwein and is left with 70 ct and cannot buy anything further. Terence checks his ...
0
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2answers
237 views

Handbag question

One day, you are shopping in a town. You came across a handbag you wanted to buy. The handbag costs ? coins. It is said that solving a logic question could earn you enough coins to buy the handbag. a ...
3
votes
1answer
184 views

Fractional part of integers within a specific interval

Three positive integers $a,b,c$ have the property that $b > 2a$ and $c > 2b$. Is it always possible to find a real number $r$, such that each fractional part of the numbers $r\cdot a$, $r\cdot b$...
2
votes
2answers
345 views

Minimum number of questions?

This is an interesting puzzle which I've been racking my brain to solve for some time. I've found different variations of this puzzle but it does not seem like this one has been asked before. Here it ...
13
votes
5answers
840 views

Evaluation of points in a contest

In a contest there are 10 questions asked, which have to be marked as true (T) or false (F). You get 1 point for a correct answer and 0 points for a wrong answer. Joe, Jack, William, and Averell are ...
4
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2answers
454 views

Very close to solve the sudoku puzzle but yet not solved

I found an X-Wing pattern using 1's on r29c48 and eliminated the 1's on r1c8, r3c8, r7c8, and r3c4. Lots of elimination but that was not helpful for me to crack it. I think I am very close to solving ...
2
votes
1answer
110 views

Find the missing letter (Alphabet puzzle)

What letter replaces '?' in the stack? How do you arrive at it? Source: CSIR NET December 2018 QP
-2
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3answers
243 views

how much does my bag weigh [closed]

I have a bag of money and I've offered to give you the bag if you can estimate its weight closer to the true weight than I can. In order to help us, I bring out 2 scales, both of which are inaccurate, ...
6
votes
3answers
2k views

Is there anywhere else I can go without guessing randomly?

I’ve been looking at this board for a little while, and can’t seem to find any places to go where I don’t have to guess. Is guessing the only thing I can do here, or are there strategies that I’m ...
1
vote
1answer
146 views

How do I know where the bombs are?

I’m not sure how I would know, because in the top right corner, where there is a 2, 3, 2, going down, the bottom two needs to touch two mines and so does the top. But if I did the immediate right ...
0
votes
1answer
111 views

Is there any sudoku logic on 6's?

I find this sudoku puzzle very difficult. I think there is some logic on 6's.
0
votes
1answer
134 views

How could I have known not to go here?

How could I have known not to press where the red bomb is?
32
votes
2answers
3k views

Three missing digits in 42 factorial

When calculating $42!=42\cdot41\cdot...\cdot2\cdot1$ the result is $42! = 140500611775287989854x14260624y511569936384z00000000$ However three digits have been replaced by $x$, $y$, and $z$. Can you ...
0
votes
2answers
100 views

Which sudoku logic should I apply here?

I was able to eliminate 1 in r8c1(in short selected cell) using Finn X wing using 1's on r17c15 and Finn is on r7c3. But it seems like that logic is not enough to make it to half way of this sudoku.
2
votes
2answers
285 views

Missing logic in sudoku puzzle

I got stuck in the given sudoku puzzle. I can't find any logic to put a number in the empty block. I am playing classic sudoku Android puzzle app. Maybe it's a XY wing or empty rectangle or any other ...
7
votes
2answers
238 views

Positive integers as sum or difference of consecutive square numbers

Is it possible to represent each positive integer n in the form $n=\pm1^2\pm2^2\pm3^2...\pm m^2$ ? Examples: $1=+1^2$ $2=-1^2-2^2-3^2+4^2$ $3=-1^2+2^2$ $4=-1^2-2^2+3^2$
-3
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2answers
190 views

The mule, the donkey and the zebra

Let's have thirteen stalls, equidistantly spaced. In each stall is a trough which contains four liters of water. In the first stall is a mule, in the second is a donkey and in the eleventh is a zebra. ...
22
votes
1answer
1k views

The Tree is Growing

I just found this new type of puzzle and I think the rule set is fun! So, I decided to create one. Rules (taken from the original puzzle): Create non-intersecting non-looping trees such that the ...

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