# 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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### 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 ...
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### 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. ...
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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 ...
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### 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 ...
348 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. ...
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### 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 ...
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### 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 ...
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1 vote
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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?
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### 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 ...
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### Can the solution a) of the accepted answer to the "Camels crossing a bridge" problem be extended to arbitrarily many camels?

This problem (and solution) with 5 camels each was posted here on Puzzling several years ago: Two merchants have 5 camels each. One fine day, one of the merchants sells all of his goods in the market ...
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### Finding a 3-digit passcode from 4 mastermind clues

What is the logic used to solve this problem?
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### Logic in the Polycule

Heavily based on a puzzle from Brainteasers and Mindbenders. Eve's anniversary with her polycule is tomorrow, and she's bought presents for all of her partners. However, she stashed the presents in ...
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### Fill the circles with the numbers 4, 5, 6, ... 10

Using all the numbers 4, 5, 6, ... 10 exactly once, fill each empty circle with a number so that if two numbers are in circles that are joined by a line then their difference (in absolute value) is at ...
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1 vote
268 views

### Fox and rabbit on a circle

There are five holes in a line. One of them is occupied by a rabbit. Each night, the rabbit moves to a neighboring hole, either to the left or to the right. Each morning, a fox gets to inspect a hole ...
351 views

### An Infinitude of Perfidious Pupils

Here's an original puzzle I created. Enjoy! A teacher had infinitely many students, and he referred to them by the designations $\text{Student } 0$, $\text{Student } 1$, $\text{Student } 2$, and so on....
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### Operator! Some Product!

Happy Venndredi all, A relatively straightforward one! The three overlapping ellipses form seven curved regions and there are seven tiles. Your task is to place exactly one tile per region so that ...
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### Tropical Rhythms

This is part 29 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a diagramless crossword. The clues are not numbered according to their ...
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