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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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6
votes
1answer
138 views

Find the immediate square dancing neighbors, they dance together to perfect square

We live in a community of houses sequentially numbered from 1 to 100. We all love square dancing but only two immediate neighbors are joy to watch. If you concatenate their house numbers, it forms a ...
17
votes
2answers
2k views

We are two immediate neighbors who forged our own powers to form concatenated relationship. Who are we?

Our concatenated number is $ \overline{ABAC}, $ where $ A, B, C $ are all positive digits (1 - 9). Our relationship is $$ \overline{ABAC} = A^A + B^B + A^A + C^C $$ Who are we?
9
votes
1answer
609 views

Narcissistic cube asks who are we?

I am a five digit narcissistic cube who likes to display my root right upfront. I also have hidden it in the back of my four digit cube brother. Who are we?
1
vote
2answers
336 views

Placing rooks on a chessboard

We have a big chessboard with N rows and N columns (numbered 1 through N). Let's denote the square in row r and column c of the chessboard by (r,c). We want to place some rooks on the chessboard in ...
7
votes
1answer
152 views

Emoji-Mutating Machines

I have built twelve emoji-mutating machines, each of which changes one characteristic of an emoji—for example, adding glasses, removing a tear, changing a smile to a frown, and so on. Each machine has ...
-9
votes
1answer
109 views

Number of days in a normal year expressed with five consecutive positive integers [closed]

Given $D$ is the total number of days in a normal year $a$, $b$ are positive integers $P$, $Q$, $R$, $S$, $T$ are consecutive integers Figure them out by combining the following six expressions ...
-2
votes
2answers
176 views

Complete the following verbal analogy!

MAKE : DALE :: (?) : PALE Hint: pattern recognition or semantical relation (?)=solution containing 4 letters : means 'to' , :: means 'as'
1
vote
3answers
482 views

Solve for the Number in the number..square..cube relationship

Each letter stands for a distinct digit...no computer or calculator needed. Just pure logic and some mental multiplication. CUBE is a concatenated number and it is a cube. X denotes multiplication. (...
62
votes
4answers
4k views

Gerrymandering Puzzle - Rig the Election

The following graphic is a map of the country Mathlandia: You are currently running for reelection, but the polls aren't exactly in your favor. Each square in this grid is a county. Counties with a ...
3
votes
2answers
145 views

SafeCracker #1 - Look who's talking

The Plot You work for a tech company in Tampa, FL. Recently there was a break-in, and the company's trade secrets were stolen. Company PI have tracked the briefcase containing the secrets to the ...
2
votes
1answer
90 views

The NANNP Grid ( Not another Next Number Puzzle )

Simply figure out the last row...
11
votes
7answers
2k views

Missing Piece of Pie - Can you find it?

A piece is missing! What should it be?
0
votes
1answer
76 views

Place Your Bets 3 , last of the series

A harder sequence to figure out... What are the next 4 cards, including suits?
1
vote
1answer
52 views

Place Your Bets 2 - In sequence, of course

Your Cards... You have to figure out what the next row of 4 cards will be. There is a pattern in there somewhere, promise. Good Luck
2
votes
1answer
88 views

Place Your Bets - in sequence, of course

Your Puzzle There is some sort of pattern in cards below. Simply figure out what the next card should be. Note: You cannot re-use a card already in play.
3
votes
2answers
93 views

A Wine Problem for Puzzlers [duplicate]

Simple Follow the instructions on the label. In case you the image is too small, Given three bottles: 8, 5 and 3 liters capacity, divide 8 liters in half (4 + 4 liters) with the minimum number of ...
15
votes
2answers
2k views

Virus Detected - Please execute anti-virus code

Virus Detected!!! Your computer, which is represented by the grid pictured, has been infected. The bugs are clearly marked. It's your job to inject your awesome anti-virus code in the proper computer ...
2
votes
0answers
133 views

The Bad Clue Puzzle

The Jumbled Story Johnny might have had a couple beers when putting this one together. What he intended was a logic puzzle of friends, their favorite classic computer system, and how they used to ...
-1
votes
1answer
94 views

The Puzzle of Puzzles - Pieces of Logic

The Story Johnny has added several new jigsaw puzzles to his somewhat large, and unusual collection this year. He likes Computer related puzzles, and the outdoors, as well. Your job, Determine each ...
1
vote
3answers
239 views

Can someone solve this kakuro?

Can someone solve this? Please tell me how you did it. Source: Puzzle Page app
-4
votes
1answer
223 views

Write an equation using constants e, i, pi and phi [closed]

Without using numbers and using only permitted math operators, write an equation using the constants $e$, $i$, $\pi$ and $\phi$. Allowed operators..exponent...multiplication..subtraction...only. Use ...
6
votes
2answers
265 views

Top Game Developers

Top Game Developers Back Story Okay fellow puzzlers, I hope you packed your lunch, this one is my most challenging puzzle to date... Johnny is writing an article about some of the top-selling ...
5
votes
1answer
142 views

Video Game Auction - Logic Puzzle

Puzzle Difficulty: Very Challenging The Story Johnny loves his classic video games. He has collected most of them. Unfortunately, though, Johnny's Grandmother needs an expensive operation. He has to ...
6
votes
1answer
240 views

Dividing the gold

There is a king and 3 women in a castle. One day, the king give 3 women a total of 100 golds. He said that each woman can propose an idea to share the gold among themselves. If the proposal passed ...
4
votes
2answers
173 views

Hidden Treasure Logic Puzzle

Ok, fellow puzzlers, here is my latest puzzle. They are getting progressively harder. Back Story While snooping around your grandpa’s attic, you came across a bunch of scribbled notes. They were in ...
3
votes
2answers
161 views

Looking for a Logical Puzzle with Scalability

I hope I am in the right place to be asking a question like this! That being said, I am experimentalist in need of a 'good' logical puzzle. There are aspects of the puzzle I would like and other ...
19
votes
5answers
1k views

Single Colour Mastermind Problem

Imagine we're playing a game of mastermind with the usual eight colours, only this version has six holes across in which to place colours. And to make it easier for you I tell you that I have filled ...
1
vote
2answers
169 views

How many oranges did the litte girl originally have? [duplicate]

Please note: "She never had to cut an orange".
12
votes
12answers
5k views

Coin Game with infinite paradox

Here’s the puzzle/problem: Let’s presume we are best friends. I own the house next to you. I make a gaming proposition along the following lines: You throw a coin over and over again. So long as it ...
1
vote
2answers
208 views

Sequence made of symbols

(My friend in real life gave me this)That's the original sequence: ⬅↕➡,⬅↕,➡,⬅,?,?,↕➡ I'm going to use other symbols to make it readable: (/), (/,), (/, ?, ?, /) I've noticed that the comma ...
12
votes
1answer
602 views

Reflections in a Square

An ideal billiards table (no friction, ideal reflections off of the walls, no pockets) is shaped like a square. From the bottom-left corner, shoot a point-sized cue ball at some angle. What is the ...
10
votes
1answer
624 views

Girl Hackers - Logic Puzzle

StackExchange Top Ranked Girl Hackers The Stack Exchange Hacking Federation (of course fictitious) has just released its list of top-ranked female hackers for the year. Using only the clues below, ...
18
votes
9answers
1k views

One-one communication

5 people are standing in a circle - person A needs to tell his salary to person B, but none of the others should know A's salary. How is this possible, if every person only whispers to the person on ...
4
votes
6answers
2k views

Find 108 by using 3,4,6

Assemble a formula using the numbers $3$, $4$ and $6$ in any order to make 108. You may use the operations; $x + y$ $x - y$ $x \times y$ $x \div y$ $x!$ $\sqrt{x}$ $\sqrt[\leftroot{-2}\uproot{2}x]{...
12
votes
5answers
2k views

Sum letters are not two different

The following letters all have something in common which may not be obvious at a first glance: A B D H P No other letters share this attribute. Hint More ...
10
votes
2answers
1k views

8 Prisoners wearing hats

A warden lines up these prisoners. He announces, "I see a white hat." He then leaves the room. Every few minutes he comes back in and asks if anybody knows their hat color. Anyone who figured it out ...
3
votes
5answers
372 views

A story about liars

Evelyn, Skylar, Alayna, Madelyn, Jonathon, Lara, Alyin, Felix, Iris, Bob and Roslina live on an island where some people always tell the truth, and the rest always lie. Roslina says "Alyin and Evelyn ...
43
votes
11answers
8k views

3 doors, three guards, one stone

You are in a room with three doors. Behind two of them, the darkest pit of hell waits for you to make a mistake. The other door leads to heaven and freedom. Each door is guarded by a guard: Michael, ...
5
votes
3answers
408 views

Can't figure this one out.. What is the missing box?

I've been stuck on this for ages, and can't figure this out. What is the missing box, and the logic behind the answer? This was taken from a Korn Ferry Leadership Assessment practice trial.
2
votes
1answer
175 views

Pattern Recognition: $7 \star 8$ =?

The following pattern was given to me by one of my friends: If $$\quad 5 \star 5 = 10$$ $$\quad 6 \star 6=18$$ $$\quad 7 \star 7=36$$ then $$\quad 7 \star 8 = ?$$ a) $54 \quad$ b) $51 \...
4
votes
4answers
176 views

What is the minimum High Card Points needed for a partnership to be able to claim all 13 tricks in Bridge?

Assume you have basic knowledge of how a contract bridge game plays. There are 40 total HCPs in a set of cards. 4 for each Ace, 3 for each King, 2 for each Queen and 1 for each Jack. What is the ...
5
votes
2answers
532 views

Gold, silver and bronze in the balance

Equivalent to finding three heaviest coins in order of weight, on a balance that holds one coin on each side. (Simplified, with some Wikipedia references corrected, from the original puzzle. The ...
27
votes
12answers
2k views

Shapes and letters. What is the missing box?

Finally, someone has figured it out. Good job.
5
votes
3answers
271 views

What's the hand of the lonely man?

Albert, Fred, Larry, Ron and Patrick are playing cards at Albert’s house with a regular 52 card deck that is missing all the 2s. Patrick has 10 cards, none of which are higher than 6. Ron has 13 cards,...
7
votes
1answer
204 views

Pattern Recognition problem : $… ,224,8,3,4,11,…$

The following pattern was given to me by one of my friend: $$\color{red}{224}$$ $$14 \quad \quad 8$$ $$4 \quad \quad \quad \quad \quad 3$$ $$8 \quad \quad \quad \quad \quad \quad \quad 4$$ $...
7
votes
3answers
405 views

Writing differences on a blackboard

The numbers 25 and 36 are written on a blackboard. At each turn, a player writes on the blackboard the (positive) difference between two numbers already on the blackboard, if this number does not ...
21
votes
8answers
10k views

Which one is the true statement? [closed]

All five statements below are true. None of the four statements below are true. Both of the statements above are true. Exactly one of the three statements above is true. None of the four statements ...
-2
votes
1answer
575 views

Don't be Greedy

this is a cs50 puzzle day 2019 question as you would know the questions have a one english word answer. will someone like to collab with me to solve all of them? there are 10 more of them.
11
votes
2answers
319 views

Bold, vivid family

I remember organising the colours of the rainbow in columns. In the way that I did, I could create the word RAINBOW from certain letters in each word, indicated by the columns they were each placed in....
12
votes
3answers
511 views

Masyu puzzles with many circles

The rules of Masyu: Make a single loop with lines passing through the centers of cells, horizontally or vertically. The loop never crosses itself, branches off, or goes through the same cell ...