Questions tagged [keys-and-locks]
For puzzles about using keys to open locks and doors.
21
questions
10
votes
4
answers
2k
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A strange construction of locks
This gate is locked with 6 locks. What is the purpose of this construction?
- 36.3k
14
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8
answers
4k
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2 Guards, 3 Keys, 2 Locks
There are 2 guards: one only tells the truth, the other only lies.
There are 2 locks and 3 keys: each lock can only have 1 key matched - the 3rd key doesn't do anything.
You can only ask one ...
- 551
1
vote
1
answer
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views
Out Of Bounds Puzzle [Level !]
Unlock the lock with the key.
You might want to put this next to a certain website's url. It was a gift to another website, if you've read it before.
/a/8QemVeM
Is enough said already?
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17
votes
9
answers
7k
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Salesman's claim for mechanical keypad lock - 5 buttons and 545 combinations!
A company makes mechanical keypad locks.
The keypad is a set of five buttons arranged vertically.
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The buttons are quite close together. Once a ...
- 4,261
7
votes
2
answers
459
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Identical-Looking Keys on a Ring
The number of keys on your key ring has been growing steadily over time, and now you already have 15 keys to keep track of! Unfortunately, you are unable to distinguish one key from another (apart ...
- 14.5k
1
vote
2
answers
443
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Is my childrens' answer a correct one to this puzzle?
On another SE site (here ) I found the following puzzle.
Suppose we have, say, a hundred open locks, numbered from 1 to 100. The riddle is the following: you hold a key which opens one of the locks. ...
- 1,136
16
votes
6
answers
3k
views
Do you have my spare key?
I have three bicycle locks, ones like this:
Because they look so much alike I etched a unique number into each lock and the same number into the keys that unlock it. Unfortunately I seem to have lost ...
- 292
8
votes
2
answers
2k
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Keypad Door Lock
Your progress is barred by a locked door, it is clearly controlled by a keypad. with 10 digits (0-9) plus a button for ENTER and a button for CANCEL. You know several things about this lock:
This ...
- 183
2
votes
11
answers
973
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What's the door code? [closed]
You're running late to your first day on the job and after arriving at the meeting location, you see the orientation group just leaving without you through a door with a keypad.
Panicked, you confirm ...
- 6,077
7
votes
2
answers
1k
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Key and lock puzzle
The idea is to place all the yellow keys into the red locks. There is at least one guaranteed way to do this as the locks as created from the keys and then 'blurred' by adding extra gaps. Solutions ...
- 35.6k
17
votes
9
answers
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Agent 001's faulty delivery box
There are 10 agents living at their respective homes. They used a secret mailing system that sends one box at a time, but it is now spoilt. Now, it functions as follows:
It counts the number of ...
- 7,016
10
votes
2
answers
812
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$100 + n$ boxes for the king!
There are 100 friends and $n$ enemies in a room. In the next room, there are $100+n$ open boxes, and $100+n$ keys, one corresponding to each box. They are numbered for easy identification. A box can ...
- 7,016
12
votes
3
answers
3k
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Cracking a combination lock
Let's consider the humble mechanical combination lock. The basic type has $n$ dials, with $k$ digits on each dial, for a total of $k^n$ possible combinations. (Typical luggage locks or suitcase lock ...
- 18.9k
7
votes
2
answers
697
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Lock Optimisation
In a simple combination lock, a sequence of several digits is used as a password, with one wheel per digit. Generally, it is not possible to unlock the lock without knowing the password, but due to ...
- 4,010
12
votes
5
answers
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One Hundred Lockboxes, Variant
You have one hundred lockboxes, fifty made of steel, fifty made of wood, and a key for each box.
A prankster breaks into your house and distributes the keys among the boxes. He places each key in a ...
- 32.5k