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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Weighing Coins -- a Different Approach
This is a question of my own devising. You have a double pan scale which will tell you whether 2 coins or 2 groups of coins weigh the same or whether one side is heavier than the other side. You have ...
- 830
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Identify the truth teller, the liar and the spy
Beginner puzzle
This puzzle is intended to be suitable for people who are new to puzzle solving.
Clarification: Both experienced solvers and new solvers are welcome to post solutions to this puzzle.
...
- 13.5k
7
votes
1
answer
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Colombian Sudoku, Cows and Bulls again…
Fill the sudoku on the left so that each column, row, box, and colored box of the same color contain the numbers 1 to 9. The dots show how many numbers in the row or column of the grid on the right ...
- 623
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3
answers
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Knights, Knaves, and Spies
I need help understanding this problem.
An island has three kinds of inhabitants: knights, who always tell the truth, knaves, who
always lie, and spies, who can either tell the truth or lie. You ...
- 39
4
votes
1
answer
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Largest prime number erroneously erased when finding all primes less than 1000
Chicharron is a lover of mathematics and once wanted to find all primes less than 1000. He did by the following steps below:
He wrote all the numbers from 2 to 1000.
He circled the number 2 and erased ...
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Brooklyn Nine-Nine: Holt’s Season 2 Puzzle [closed]
I’ve seen several answers to the Weighing Islanders puzzle Captain Holt poses to the squad in Season 2, but I had a different train of thought when solving it. Did anyone use the process of ...
2
votes
1
answer
189
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What is the name of this puzzle type? How to create one? nxn grid where you select n cells with different numbers
I want to create a specific puzzle, but I'm wondering if it already has a name, and if I can find some pointers on how to make it hard.
I have a NxN grid filled with numbers going from 1 to N.
I want ...
- 23
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Fill the triangular grid using the digits 1-9 subject to the constraints provided
Fill the grid using the digits 1-9 four times each. No row or column can contain the same digit more than once. The total of each row and column is provided, as well as clues to the numbers forming ...
- 13.5k
4
votes
3
answers
818
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Eliminate some numbers so that each of the three rows contains the numbers 1 through 9 each exactly once
Beginner puzzle
This puzzle is intended to be suitable for people who are new to puzzle solving.
Clarification: Both experienced solvers and new solvers are welcome to post solutions to this puzzle.
...
- 13.5k
30
votes
1
answer
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Are you radical enough to solve this SURDOKU?
All "surds" represent whole numbers smaller than 15, and the same number is never used twice with the same index. (It's a sudoku.)
Attribution: PUZZLEBOMB.co.uk. Puzzles by @stecks & @...
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Fill the grid subject to product, sum and knight move constraints
Using the numbers 2, 3, 4, ... 19 each exactly once, fill some of the empty squares in the grid with a number so that the product of the numbers in each row is as shown, as is the sum of the numbers ...
- 13.5k
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1
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Next date in the future that satisfies the following conditions
When is the next time that a date will satisfy the following conditions:
YYYY days from MM/DD/YYYY is also the (DD)th day of a month. Note that YYYY stands for the year.
All eight digits of MM/DD/...
- 285
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Why math is hard to understand or explain in reverse [duplicate]
Three people go into a restaurant and each of us has \$10. So we start with \$30.
The bill comes to \$25 which means there is \$5 left over. Out of that \$5 we each take back \$1 (which would be \$3 ...
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1
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A colourful Colombian Sudoku
Fill the sudoku on the left so that each column, row, 3x3 box, and cells of the same color contain the numbers 1 to 9. The dots show how many numbers in the row or column of the grid on the right ...
- 623
15
votes
1
answer
687
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Tombs of Ancients
This is part 68 of the puzzle series Around the World in Many Days. Each part is solvable on its own.
Dear Puzzling,
The top grid here is a Yin-yang puzzle. Shade some cells in the grid so that ...
- 78.9k