Linked Questions

3 votes
1 answer

100 Cards with numbers in a room [duplicate]

The scenario is like this: There's a room, inside the room there are 100 cards with numbers [1,100] on them (No duplications), the cards are ordered randomly. Two persons stand outside the room, ...
StationaryTraveller's user avatar
1 vote
1 answer

Don't Fail MY Exam [duplicate]

A professor decides the following grading scheme in his class. After the final exam is graded, he keeps all the papers upside down on his table in a random order so that no student can recognise his ...
dvc's user avatar
  • 61
62 votes
5 answers

How to beat Count Dracula

Abraham Van Helsing and Jonathan Harker play a game against Count Dracula. The three players agree on the following rules: Count Dracula and Van Helsing enter the crypt, while Jonathan Harker ...
Gamow's user avatar
  • 45.4k
11 votes
5 answers

Two player Monty Hall variation

Alice and Bob are going on a game show as partners. In this game, there are three doors, which contain a car, the car keys, and a goat, which are arranged randomly and secretly behind the doors. Alice ...
Nuclear Hoagie's user avatar
17 votes
5 answers

100 Prisoners' Names in Boxes - Save them all!

This puzzle is based on 100 Prisoners' Names in Boxes: Names in Boxes The names of 100 prisoners are placed in 100 wooden boxes, one name to a box, and the boxes are lined up on a table in a ...
durron597's user avatar
  • 2,344
11 votes
4 answers

How to rate difficulty of a classic riddle?

How, as a writer of riddles, can I rate their difficulty? I guess, for me alone, knowing the answer even before the riddle existed, it's pretty much impossible, and I should need some external help. ...
SF.'s user avatar
  • 1,366
11 votes
4 answers

Help me find my favourite DVD

I have an admission to make: I very rarely put my DVDs back in the case they came from. Whenever I watch a new DVD I just put whatever DVD is the player in the new case. I put the cases back on the ...
CJ Dennis's user avatar
  • 386
5 votes
1 answer

Shuffling Cards

I was just thinking about this. Let's say that we have a card deck with 54 cards and the $n$th card from the top is flipped. We repeat a short process of cutting the deck directly in the middle and ...
awesomepi's user avatar
  • 2,969
13 votes
2 answers

Let's deal with "Names in Boxes" Safely

I met a puzzle, which is basically well known 100 Prisoners' Names in Boxes , but... it has an algorithm, which gives prisoners 100% chance to survive! This is achieved by a small change in the ...
klm123's user avatar
  • 16.1k
5 votes
2 answers

100 prisoners' names in boxes, against smart warden

My question, which I do not know the answer to, concerns the classic 100 prisoners and 100 boxes puzzle, summarized below. The solution to this assumes the names are placed in boxes randomly, and gets ...
Mike Earnest's user avatar
  • 32.1k
6 votes
2 answers

A "Puzzling" Cipher

I thought I'd put together a simple cipher for all of you Puzzling lovers out there. If you need help, you can always look to the wisdom of the past for guidance. The answer is a single word, and each ...
DqwertyC's user avatar
  • 8,071
3 votes
1 answer

Variation of 100 Prisoners' names in boxes

100 Prisoners' Names in Boxes The following puzzle is a variation of the above puzzle. Names in Boxes The names of 4 prisoners are placed in 4 wooden boxes , one name to a box, and the boxes are ...
Hemant Agarwal's user avatar
1 vote
0 answers

100 boxes, only 50 attempts [duplicate]

There are 100 boxes in the room. In every box there is a note with some number from 1 to 100 (no repetitions).Person A comes into the room and checks all the boxes and notes inside them. He can (doesn'...
Miriam's user avatar
  • 11