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).
2,144
questions
1
vote
1answer
107 views
The Big Cube and Squares Puzzle
The following logical puzzle is mainly inspired by a mathematical contest I went to.
Part A
You are given a cube. How many planes cross this cube by at least 3 vertices? This number will be named $...
4
votes
1answer
120 views
Project Projection
The Project
You and a co-worker have been assigned to complete a web application.
The client wants to know how many hours the project will take to complete - the minimum.
Your Puzzle Task
You need ...
5
votes
4answers
365 views
Where to pitch the next tent?
I am stuck solving this "Trees and Tents" puzzle. How to solve the rest of the puzzle?
For does who don't know the puzzle, these are the "Trees and Tents" rules:
A tent must be placed next to every ...
6
votes
0answers
189 views
Solution without words
Here comes a series of snapshots in the life of a worksheet
that might come into play when solving a variation of
a fairly-well-known numerical logic puzzle.
Parameters of the progenitor puzzle ...
0
votes
0answers
158 views
Reverse Engineering Computer Formula
A computer uses an unknown formula to create a 4 digit Output using specific Input. Here are 3 examples:
Input = 20066 : 020470 : 47 : 1 : 322267 Output = 0927
Input = 20066 : 020470 : 46 : ...
3
votes
1answer
188 views
Another puzzle for who has long boring days
The rules:
each row must have the digits from 0 to 9.
The sum of the digits in the column is shown at the bottom of the column.
The same number can appear more than once in a column.
Adjacent boxes ...
0
votes
0answers
81 views
unsolvable Number pattern [closed]
This is the sequence:
24, 333333, x, x, 53, 44444444, 82, x, x, 222244444444, x, x,x, 444433333322221
In this sequence we could consider those couples:
24,333333
x,x
53,44444444
82,x
x,...
-2
votes
0answers
118 views
3
votes
1answer
280 views
Complete the series:
$4427, 827, 67, 31, 9, ?$
Choose between:
(a): $7$
(b): $6$
(c): $5$
(d): $4$
Looking at the numbers I think that there must be some exponential relationship but couldn't find it. I took the ...
9
votes
1answer
235 views
4
votes
2answers
167 views
4
votes
5answers
706 views
Place the numbers 1-7 in the squares so that each row and columns adds up to the same total
A F
B D E
C G
A+B+C = B+D+E = F+E+G
Numbers 1,2,3,4,5,6,7
11
votes
1answer
280 views
humans, vampires and mirrors
Here is a room composed of $10 \times 10$ squared cells. Some cells contain a double-faced mirror ( / or \ ) that reflects the light with an angle of $90°$ on both sides.
The other cells can be empty (...
27
votes
5answers
2k views
How many spots do these frogs have?
You are approached by 5 spotted frogs who appear to be venomous, to avoid getting bitten by them, you must find out how many spots they have. The frogs with an even number of spots always tell the ...
9
votes
3answers
398 views
Number Guessing (Part 1)
I thought up two positive integers with product less than $500$. I told their product to Penny, and their sum to Sandy, and told both of them the constraints and they are both perfect logicians.
...
7
votes
2answers
358 views
Akari: Another Light
Rules (taken from Nikoli):
Place light bulbs (circles) according to the following rules.
Light bulbs may be placed in any of the white squares, the number in the square shows how many light ...
10
votes
3answers
499 views
Pieces of paper without consecutivity condition
TL;DR: like this puzzle but with an arbitrary number of papers and without the condition that the papers chosen must be consecutive.
You are given $n$ pieces of paper, and you write down $n$ distinct ...
2
votes
1answer
109 views
Setka Puzzle - Complete grid using clues and sudoku-style logic; Tom Hanks
Theme: Tom Hanks
This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from our profile.
How to play Setka, the short version:
...
14
votes
3answers
1k views
A mini game with 15 pieces of paper
You are given $15$ pieces of paper, you are asked to write down any distinct integer numbers on them as you wish. Then these pieces of paper will be turned back, mixed and put on the table in a ...
3
votes
2answers
137 views
Great POTW Bake-Off
Pepper, Belle, Emerson, and Ralphie have just competed in POTW’s Annual Bake-Off. Pepper, Belle, Emerson, and Ralphie each came in first, second, third, or fourth in the competition. There were no ...
31
votes
1answer
3k views
MASTERING Sudoku
Fill the grid with letters M, A, S, T, E, R, I, N and G.
Standard Sudoku rules apply.
Additionally, the words on the right-hand side must appear in the given orientation (across/down). Each word ...
9
votes
1answer
224 views
Akari: The Light
Rules (taken from Nikoli):
Place light bulbs (circles) according to the following rules.
Light bulbs may be placed in any of the white squares, the number in the square shows how many light ...
4
votes
2answers
132 views
How can I make a valid conclusion about a set of statements which are in tandem?
The problem is as follows:
If there are no government subsidies for agriculture, then there are
government controls on agriculture. If there are government controls
on agriculture, then there ...
1
vote
0answers
166 views
Math tapestry puzzle #3
Continuation from Math tapestry puzzle #2
Now things are heating up, it looks like this is slowly becoming bigger. I saw my friend Anna working on her tapestry. She asks me, "Do you like it?"
...
32
votes
1answer
1k views
This cipher needs a name!
This puzzle is a spin-off from the 'This new puzzle type needs a name' series.
I have devised a new cipher and used it to encode its own name. I need you to tell me:
What is its name?
This puzzle ...
0
votes
1answer
94 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: ...
1
vote
1answer
83 views
How can I find which sport/hobby corresponds to which friend when a set of given clues is provided?
Marina, Mike, Roger, Phillip and Justin has each only one hobby from
the following list: motocross, badminton, swimming, athletics and
karate, but not necessarily in that order. It is known that:
...
3
votes
2answers
126 views
How can I find which person belongs to a specific occupation when the clues involve degree of friendship or acquaintance?
The riddle is as follows:
Brenda, Lara, Mie and Nancy have each one profession. These
professions are, baker, graphics designer, photographer and
cosmetologist.
But not necessarily in that ...
3
votes
1answer
143 views
Fork in the road problem - with a single person
You walk to a fork from where two roads come out - one leading to a post office and the other to a university.
You want to go to the university, but do not know which road would lead you to it. A ...
6
votes
1answer
135 views
Puzzle - Snow Day Event
Daisy, Delilah, Donny, and Duke have each decided to participate in the snowperson building event.
In decorating their snowperson, each of them has chosen a different colour of the scarf from purple,
...
6
votes
3answers
220 views
A Game of Dice and Logic II
Part 1, same game rules, slightly different cards
This question is broken - my program for proper analysis failed in some catastrophic way, and the question does not work as planned.
The intended ...
2
votes
1answer
159 views
Math tapestry puzzle #1
I went outside. I saw several math tapestries. Apparently they mean something. What goes in spot NN?
I know from my friend that...
Two adjacent numbers always have the same sum.
The 4 numbers in each ...
15
votes
5answers
1k views
A Game of Dice and Logic
A friend and I are playing a cooperative game. He has two D7 dice and 5 cards in front of him. They read;
...
7
votes
1answer
147 views
Guessing the coin flips [duplicate]
Two prisoners, Alice and Bob, are captured by a dragon and placed in separate, isolated cells. The dragon then flips an infinite number of fair coins, and tells the outcomes of odd throws to Alice and ...
12
votes
2answers
2k views
It's my sister's birthday
I'd ordered her a cake, but when I got to the bakery to pick it up, the cake decorator had transposed the digits of her age.
"She'll thank you for the compliment," I said, "but her age is a prime ...
3
votes
0answers
93 views
Splitting a Grid in 4 Equal Portions [closed]
I was wondering if someone could provide a solution to this. Instructions are provided. Thank you.
7
votes
1answer
186 views
Two persons and one question “Is the shaman honest”. Which one of them is the shaman?
An anthropologist arrived to the shaman's den where there were two persons, one with a green hat and one with a blue hat. One of the shaman's students had said that there was a Star Predictor with the ...
6
votes
2answers
370 views
Puzzle - Counting Lights, Not Sheep
Some nights it is difficult to get to sleep. On one such night, John counted the
number of LEDs (Light-Emitting Diodes) on his clock radio that was on to make
each individual time from 10:00 PM to 12:...
1
vote
1answer
86 views
Setka - Complete grid using clues and sudoku-style logic; Theme - Greenwich Village Resident
This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from our profile.
Theme: Greenwich Village Resident
How to play Setka, the ...
6
votes
1answer
139 views
Cryptic Setka - Complete grid using clues and sudoku-style logic
This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from this user's profile.
How to play Setka, the short version:
Answer each ...
6
votes
2answers
365 views
Smullyan Logic Puzzle about Nelson Goodman Principle - Knights and Knaves
In Smullyan's "Logical Labyrinths" there is the following problem 1.11:
...
7
votes
1answer
154 views
Montague Island Mysteries Logic-Grid Puzzles
I'm working through the logic-grid puzzles in the book called "Montague Island Mysteries" by R. Wayne Schmittberger. The particular puzzle I'm on is Puzzle 5.3 where breakfast guests choose food ...
-1
votes
1answer
77 views
Figure out the next two numbers in this sequence [duplicate]
1,11,21,1211,111221,312211,13112221,1113213211,....?
Find the next two numbers in the sequence
This question appeared in my math competition and I managed to solve it, and I will give a hint if ...
8
votes
1answer
232 views
Can you solve this football league table problem?
Each team (A,B,C,D,E,F) plays each other once (on a neutral ground). Maximum number of goals scorable is 4. A team gets $3$ points for a win, $1$ point for a draw and $0$ points for a loss.
At the ...
2
votes
2answers
223 views
Guess the numbers
One day Bob and Alice walk around they were having the following conversation:
Bob: Alice go ahead and pick any random number.
Alice: Okay, I have one.
Bob: Alice multiply the random ...
5
votes
2answers
152 views
Is “meta”-logic valid for solving puzzles? [duplicate]
I think this question is best explained with a demonstration. In this case I'm playing a Range puzzle, but this kind of concept seems to work with other puzzle types too.
Of interest here are the two ...
14
votes
3answers
1k views
A King's Hamiltonian Tours
a) Place the numbers 1 to 25 in the cells of a 5 x 5 board in such a way that consecutive numbers occur in adjacent cells either vertically, horizontally, or diagonally, and so do cells with numbers 1 ...
5
votes
1answer
176 views
17
votes
4answers
2k views
Paint 21 Squares of a 7×7 Board Without Forming a Rectangle
Got a nice puzzle from my friend, when he was competing in IWYMIC/IMC 2011.
Paint $21$ of the $49$ squares of a $7 \times 7$ board so that no four painted squares form the four corners of a rectangle....
10
votes
1answer
256 views
Double Chocolate: Happy Valentine's Day!
Hikouki (@flight_float) over on Twitter issued a challenge to make a Double Chocolate logic puzzle with a fixed grid pattern, and lots of logic puzzle makers responded to that challenge! Here's my ...
