# 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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### 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 ...
1k views

### Logic puzzle: Driving around the United States

For Super Bowl Sunday, here's a super-sized logic puzzle! This was a practice puzzle for a hunt I participated in a few years ago. There are ten delivery drivers driving around the United States of ...
10k views

### Which number should replace the question mark?

There is a picture. Find out what number is needed to replace this question mark.
270 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,...
199 views

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### Pattern recognition problem: if $2 \star 8 \star 8 = 161642\dots$ then M=?

The following sequence was given to me by one of my friend: $$\color{red}{2 \star 8 \star 8 = 161642}$$ $$\color{blue}{4 \star 9 \star 7 = 362843}$$ $$\color{red}{7 \star 5 \star 9 = 356344}$$ ...
137 views

### Tokyo Metro puzzle special: Oops, the lines are coming down

Here is my first Special Edition puzzle, and it is a little harder. The map is also available as a PDF. So you, being a Tokyo straphanger, was in between Hikawadai (Y05 F05) and Kotake-mukaihara (...
1k views

### A first choice die

You and your friend have met to play a game of dice. This is a very simple game where both players roll a die at the same time, and the player with the lower score pays a coin to the other player. In ...
249 views

### Unlock an answering machine using minimum number of digits

You know of answering machines with a remote inquiry facility, where you can call the answering machine and enter a four digit passcode into your telephone keypad, so you can listen to your messages ...
972 views

### Treasure Hunt Riddle

John and Peter participate in a treasure hunting competition. The organizer places a gold medal in one of the lockers. The locker rack contains 49 lockers, each of which has a name indicating its row ...
477 views

### Guess simultaneously, color of your hat, no passing allowed

1000 logicians standing in a circle are blindfolded and a hat of either black or white color is placed on each person's head. The blindfolds are then removed and each person can now see everybody's ...
374 views

### Houses and Telephone #s

There are 16 houses consecutively numbered 1-16. All houses have 7-digit telephone numbers, numbered consecutively, in the same order. For example, if house #3's phone number is 1111111, house #4 will ...
209 views

### systematic number removal [duplicate]

The whole, natural numbers 1 through 50 are written on a board. The following operation is performed 49 times: select any two of the numbers on the board and write the absolute value of their ...
424 views

### Analyzing Single-Elimination Tournaments

I know there are many questions/answers about single elimination tournaments out there, but I wanted to approach this question in a more holistic way. For a single-elimination tournament with N ...
249 views

### Integers in Cells puzzle (sudoko-like)

All the whole numbers 1−9 are placed in the 9 triangular cells. A negative sign is placed in front of some numbers. The letters A−F are products of 3 or 5 of the numbers. Find all possible ...
4k views

### The No-Straight Maze

Consider the following maze. You can walk on the black lines, and your aim is to go from the green at the maze's bottom to the red on the left side. However, each time you reach an intersection of ...
7k views

### Crack the 5 digits code

I created this "crack the code" puzzle. I hope the members here like it.
5k views

### XKCD inspired logic puzzle

I came up with a logic puzzle inspired by this xkcd comic. I don't yet have an answer, and I am wondering if anyone can come up with one. You are in a room with three doors. Two of the doors lead ...