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Questions tagged [logical-deduction]

A puzzle that needs formal logical deduction to arrive at a solution.

7
votes
1answer
1k views

A Pair of Odd (but Still Balanced) Dice

I have a pair of odd six-sided dice at my house... I don't quite remember where I got them. Each die has only one number on each side, and each of these numbers is a positive number. Each pair of ...
3
votes
1answer
121 views

need help in solving that numerical sequence

Sequence: 2, 3, ?, 8, 6, 7, 6, 5, 9, 3, ?, 1 I've tried to figure out what number I should replace to the *?*I have initially thought that was a modified fibonacci sequence example: we start with 2+3=...
0
votes
0answers
100 views

Can’t find the answer to this puzzle [on hold]

I’ve been told it’s in the colors.
8
votes
8answers
366 views
+50

I'll have this one!

Through the web and morning view. Break from rise, it's perpendicular too. It can be rough or go on forever. Lets finish this rhyme by thinking about leather! What is the subject? Hint 1 Hint 2
0
votes
1answer
66 views

Heyawake - how to continue?

Can you help me find the next move. (The cells marked with dots must be white).
4
votes
1answer
146 views

Reena and the doors. How many?

Caution: You are entering a boring adventure zone You need to follow Reena's morning routine and answer the question: How many doors did Reena physically open? (Total number of times she opened ...
13
votes
3answers
953 views

Shannon O'Hannan Public School Puzzle Contest Winner 2019

This puzzle won the Shannon O'Hannanan Public School's Puzzle Club contest. As the prize, we are letting the winner type out his puzzle on the Puzzling Stack Exchange for all of you to solve. Our ...
0
votes
0answers
68 views

Funny little riddle [duplicate]

Here is a funny little riddle : 3111 = 0 1234 = 1 8765 = 3 1989 = ? No more hints, it should be enough to find the solution
8
votes
3answers
2k views

Folding a paper wouldn't be this hard

Alice and Bob started to play a game with a piece of A4 paper. Alice is going to cut that paper as she wants and will give it to Bob, then Bob will fold the paper from anywhere he wants. In the game, ...
-4
votes
0answers
114 views

Numerical sequence

That's my last post for the week, I need help in solving this numerical sequence: ?, 36, 36, 18, 16, 14, ? I don't see any correlation between these numbers. Source:http://zagaza.ru/za548.htm ...
-4
votes
0answers
105 views

mathemathical-logical sequence solving

I need help in solving this sequence: 24, 333333, ?, ?, 53, 44444444, 82, ?, ?, 222244444444, ?, ?, ?, 444433333322221 reposting this because I wanted to add more informations. Now by taking a look ...
8
votes
8answers
988 views

What mysterious whole number am I?

From my second point of view I copy that amount of first. I am the dominant side of two but for many I'm the worst. I'll be tricky to find but today might be your day, after all my neighbour is 2/3 of ...
2
votes
1answer
83 views

Heyawake - help continue puzzle (2)

Hint needed. The cells marked with dots must be white.
1
vote
1answer
133 views

Sequence solving

I need help to find the x: 6 3412 x 8605648 I've noticed that the end doubles everytime so we have 6 then 12, then we should have 24 then 48 , I have also noticed that the first 2 numbers ...
1
vote
1answer
67 views

Heyawake - help continue puzzle

This is my first try on Heyawake and I am stuck. Can you give a hint for the next move. The cells marked with dots must be white.
1
vote
2answers
147 views

Number sequence solving

Help me solving this sequence: need help 9,?,342,675,1230, ?,3561,5892 Source: http://zagaza.ru/za548.htm
1
vote
1answer
131 views

Solve this sequence -pattern

Ok,I need to find the solution to this sequence: 1.(09), 1.(4), 2, 3, ?, 17 the number in parentesis is an infinite decimal like 1,099999 or in the second one 1,4444444,but i can't find an answer for ...
77
votes
7answers
15k views

Thanks, dad! Never again

No idea why my dad dragged me into this place. Some guy is performing on the stage. He's reading numbers out loud. I think it's some kind of a sequence puzzle. 1... 8... 9... 16... 17... ...
1
vote
2answers
213 views

Pattern recognition sequence with numbers

I think I have solved this one, but I've got 2 different solutions. $$1,2,3,-1,3,2,1,x,x$$ First solution (I think this is the right one) I just noticed a pattern where the numbers between the 1s ...
7
votes
1answer
476 views

Pattern recognition using a, b, c, d, and e

I need to find the solution of this pattern: {a,b,c}, {c,d,e}, ?, ?, ?, {b,c,e}, {a,c,d}, {b,c,d}, {a,c,e}, ? The solution should be something like this: {a,b,c}, {c,d,e} {x,x,x} {x,x,x} {x,x,x}...
4
votes
1answer
667 views

Am I allowed to use the XOR operation for the “Three Gods Puzzle” AKA the “Hardest Logic Puzzle”?

So I wanted to ask something about the Three Gods Puzzle which you can read more about from here: https://en.wikipedia.org/wiki/The_Hardest_Logic_Puzzle_Ever Basically, the question of the puzzle is: ...
4
votes
2answers
400 views

The Grand Heist

One day, the police receive an anonymous tip that a robbery is about to occur on the fortieth story of a tall building. They grab a car and drive as fast as they can to the site. On arrival, they ...
-2
votes
2answers
131 views

Pattern recognition question [closed]

Here is a number sequence with a missing term: $22$, $44$, $186$, $1458$, $11680$, $?$ The first thing I noticed is that if you take the first term ($22$) do $2 \times 2 = 4$ and that's the ...
-4
votes
2answers
155 views

Come on people! what am I? [closed]

You are in a store when out of nowhere you hear a voice. It asks. what am I? It follows the question with a story. I asked a lady before and she said “I think you are a banana?” then I ...
16
votes
1answer
209 views

Diabolical Deceptions: A 333rd Birthday Tribute to J.S. Bach

Johann Sebastian Bach is one of the most famous composers from the Baroque period. If he was still alive today, he’d be 333 years old. So, let’s celebrate 3 of his most famous works with a 33x33 loop ...
-1
votes
2answers
97 views

who eats more fruits? [closed]

in a party 3 brothers discussing: first brother says " I ate more fruit than 2nd brother and 2nd brother ate more fruit than 3rd brother" 2nd brother says " 3nd brother ate more than me also 3rd ...
1
vote
2answers
186 views

I need help with this secret santa puzzle

My secret santa is playing a game with me. One of the games is a series of 6 riddles, that make up a word of 6 letters or a phrase of 6 words that help me decrypt an encrypted message through an app. ...
0
votes
4answers
180 views

What is the missing number in the picture

interesting puzzle from facebook
3
votes
2answers
210 views

The Multiple Choice Test Test

One day, the logic professor announces a pop quiz. "All questions in this test are about the test itself. In fact, the test is open note since you have a copy of the test itself. Good luck!" 1. What ...
2
votes
0answers
139 views

banana at party [closed]

At a party, three boys ate bananas. First boy: I ate more than second one and he ate more than third one Second boy: Third one ate more than second one and me Third boy: I ate the same ...
8
votes
2answers
389 views

Hat Puzzle with 5 different colours and 3 people

A dad wants to play a game with his 3 children this Christmas. He has a bag with 5 hats; 1 white, 1 yellow, 1 red, 1 blue and 1 black in it. The hats are all equal except their colour. He will place ...
-1
votes
1answer
151 views

Most efficient way to travel home for the Holidays? [closed]

A group of ten students needed to travel home for the Holidays. Not more than three of them live in the same town. At least two of them would like to visit their fellow classmates. One of them has a ...
50
votes
2answers
7k views

It's getting harder and harder not to offend anyone

Andy, Bob and Chuck are old friends meeting for the first time in years. Scene 1: At the intersection ANDY: Hey guys! Long time no see! BOB: Hey, nice to see you, Andy! Have you seen Chuck? Is ...
4
votes
1answer
412 views

Lewis Carroll's Logic Problem #1, page 386

This is one of Lewis Carroll's logic problems for which no solution was given. I have reached a solution and am looking for someone to confirm it. This problem is taken from William Bartley's book "...
7
votes
1answer
476 views

What is the Unit Digit of the Sum?

I am thinking of 2 integers $x$ and $y$ which follow the following; $$2≤x≤y$$ $$x+y≤47$$ I then write the sum $S = x+y$ and the product $P=xy$ on two separate cards. I pass the sum card to player A ...
3
votes
4answers
341 views

Horse Puzzle again

Given 8 horses and you can race any 5 of them and after every race you get the 2nd and 3rd fastest horse how would you find the fastest horse in minimum number of steps. Well the minimum number of ...
3
votes
1answer
101 views

Triskadecimal Emojis

[This puzzle is heavily based on one from video game Zero Time Dilemma.] I have one of those weird individualist friends--to give you an idea, he spells his name H-E-N-🔟-R-Y. ...The 🔟 is silent, y'...
1
vote
2answers
171 views

A couple of couples

Two couples have babies simultaneously in different hospitals. They don't know the expected gender, and each have one child which is F or M. How can they arrange in advance, given a guess each on ...
4
votes
2answers
164 views

5 Digit Code Puzzle

We have a 5 digit code, any place can take 1 2 or 3. How do I find where the 2 is placed (if placed) knowing this criteria? 1) If the 1st digit is not a 3 then the 2nd is. 2) If the 1st ...
1
vote
2answers
101 views

Intuition or Approach for this problem [duplicate]

Assume you have 8 horses and you can race any 5 of them at time. After every race you get the 3rd and 4th fastest among them. How will you find the fastest among them? What would be the general ...
2
votes
2answers
121 views

The Inducheon Conspiricy (Who is guilty #8)

At the Korean Nation Police Agency (NPA) in Migeun-dong, Seoul, researchers discovered that 73% of the Senior Inspectors (경감, 警監) all came from the small village of Inducheon. At first, they thought ...
2
votes
1answer
88 views

14sums - the diamond standard

My initial question had lots of answers, and my second had too many constraints. So, I have removed some constraints and added another. Same rules as before, but we are now using $[0,6]\cap\mathbb{Z}$....
5
votes
1answer
149 views

The Inducheon Conspiracy (Who is guilty #7)

At the Korean Nation Police Agency (NPA) in Migeun-dong, Seoul, researchers discovered that 73% of the Senior Inspectors (경감, 警監) all came from the small village of Inducheon. At first they thought it ...
1
vote
0answers
42 views

Sequence puzzle in rows [duplicate]

The below is a number puzzle. It should be read left to right, top to bottom. Question 1: What is the next two rows of numbers? Question 2: How was this reached?
3
votes
1answer
233 views

Applied logic challenge problem #2

This is similar to my previous Applied Logic Challenge Problem but with a significant difference at the end which could make this problem somewhat more difficult. Again it is a problem of my own ...
4
votes
1answer
185 views

Murder Detective (Who is guilty #6)

[This is a puzzle I've been working on. It has a unique solution. This one is meant to be one of the easier ones. Comments, thoughts and suggestions are welcome!] The suspects are Amos, Celia, Emilia,...
5
votes
1answer
109 views

21sums - more constraints

My initial question had lots of answers, as we can practically choose the middle square to be anything we want, and work outwards to the exterior edges, with the corners providing the flexibility ...
6
votes
7answers
1k views

9sums - a logical deduction puzzle

Each set of minuses contains an integer in the range [1,5]. The given numbers are the sum of the surrounding 4 numbers. --- --- --- --- 13 14 11 --- --- --- --- 11 ...
3
votes
2answers
184 views

A Criminal Conspiracy (Who is guilty #5)

[This is continuing from previous puzzles. #4 was quite tricky. This one is meant to be much easier (I'm testing the boundaries here). I've been testing various versions and would love your thoughts. ...
7
votes
2answers
220 views

A Criminal Conspiracy (Who Is Guilty #4)

[Appeal: I'm trying to figure out a fun puzzle formula. There are many out there ("Who owns the fish", sudoku, etc). I'm interested in feedback on whether this works or is interesting for people. ...