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Questions tagged [real]

For puzzles that presented themselves, with real parameters and consequences, during otherwise non-puzzling activities.

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8 votes
3 answers
623 views

Halve time with two timers

Two motorized 24-hour light timers are daisy chained between a power outlet and a light bulb. For these timers, devise schedules and choose initial times that produce the following repeated lighting ...
humn's user avatar
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8 votes
3 answers
827 views

Odd hours with two timers

Two motorized 24-hour light timers are daisy chained between a power outlet and a light bulb. For these timers, devise schedules and choose initial times that produce the following repeated 9-hour ...
humn's user avatar
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21 votes
11 answers
4k views

What's wrong with this line in a baking recipe book?

A cookie-baking recipe book (this one, specifically) has the following instruction in it, which is incorrect in a single spot: If you have a fan-assisted oven, you will need to reduce the recipe ...
user avatar
12 votes
3 answers
1k views

Day and night of the two timers

            Make a non - 24 - hour day /  night cycle       &...
humn's user avatar
  • 21.9k
9 votes
2 answers
507 views

Third timer's a charm

Three motorized 24-hour light timers are arranged between a power outlet and a light bulb, with timer A parallel to a daisy chain of timers B and  C. For these timers, devise schedules that ...
humn's user avatar
  • 21.9k
16 votes
4 answers
4k views

Is there a secret message in the first decimals of PI?

Is there a secret message encoded in the first decimals of $\pi$? Source: Vi Hart
Bass's user avatar
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5 votes
8 answers
822 views

A strange sight in London

While travelling in London, I noticed something strange. I saw some numbers which appeared to be counting up but which then switched to counting down. Later on, I saw the same thing, but the numbers ...
paolo's user avatar
  • 1,074
83 votes
2 answers
4k views

A good puzzle is a double-edged sword

A rare double-edged sword is currently on loan from the British Museum to the Magna Carta exhibition. The sword itself is described as likely made in Germany around 1250-1330 and includes the ...
Richard's user avatar
  • 5,350
78 votes
1 answer
20k views

Unsolved Mysteries: Kryptos

This is the second in a series of Unsolved Mysteries posts. These posts explore current unsolved real-world puzzles. Since these have been unsolved for years, it's uncertain whether anyone on on ...
GentlePurpleRain's user avatar
74 votes
8 answers
24k views

My friend sent me a photo of his keyboard, but there's something I can't figure out about it

Two months ago, my friend bought a new Chromebook. He told me yesterday that while he is happy with the computer overall, he's not that impressed by the quality of the keyboard. My friend is an ...
Emory Bell's user avatar
  • 1,907
55 votes
1 answer
6k views

Unsolved Mysteries: D'Agapeyeff cipher

The D'Agapeyeff cipher is an as-yet unbroken cipher that appears in the first edition of "Codes and Ciphers", an elementary book on cryptography published by the cryptographer Alexander D'Agapeyeff in ...
pacosta's user avatar
  • 691
36 votes
3 answers
3k views

Is this more than a packing puzzle?

I bought this set of wooden blocks at a garage sale today, and although it was a challenge to fit them in the box, I suspected they were more than just a packing puzzle. Can you guess what else they ...
Don Kirkby's user avatar
  • 2,602
36 votes
3 answers
4k views

Unsolved Mysteries: Magic Square of Squares

This is the first in what will hopefully be a series of Unsolved Mysteries posts. Note that this puzzle has no known solution, nor any proof that a solution is impossible. We will see how ...
GentlePurpleRain's user avatar
32 votes
9 answers
9k views

Should I Take the Bus or Refill My Bottle First?

This is a real-life puzzle encountered by one of my friends. I want to arrive early to my class today. Exactly every $7$ minutes, there is a bus that arrives at the station near my dorm and will ...
athin's user avatar
  • 34.2k
29 votes
2 answers
7k views

Does this metal puzzle have a solution (Baguenaudier)

When I was young I got this puzzle as a gift to me. The aim is to get the long piece out. I haven't yet found a solution, and I'm not sure if there is one Does this have a solution and if so ...
hazoriz's user avatar
  • 393
26 votes
1 answer
2k views

Real life puzzle: Unknown alphabet or shorthand

User JellicleCat posted this on linguistics stackexhange a few years ago. None of us were able to come up with a satisfying answer but most seemed to agree that it was an idiosyncratic cipher or ...
cyco130's user avatar
  • 361
26 votes
4 answers
4k views

The "Loop of rope" dilemma

It's a "dilemma" that I encountered in real life problems. I believe that it's not new and is quite easy to explain, but may look puzzling at first glance. Alice and Bob are playing with a ...
WhatsUp's user avatar
  • 7,407
26 votes
3 answers
2k views

This image contains a "Great Discovery"

The Puzzle: Source material taken from here As discussed on Numberphile, here is John Herschel's doodle, sent to his friend Charles Babbage. John H. John Herschel was an English polymath, ...
Ovi's user avatar
  • 403
22 votes
11 answers
5k views

Why is the pavement wet?

Saw this the other day. So I took this picture. There was another nearly identical wet patch 2 spaces away. Why is the pavement wet? Note: This is a straight forward physics puzzle. This is a ...
John's user avatar
  • 371
20 votes
5 answers
2k views

The Greenhouse Problem

While I was playing a certain popular indie farming game, I came across a dilemma. I have a greenhouse that I'd like to fill as efficiently as possible. How many plants can I fit in the greenhouse? ...
Nilster's user avatar
  • 874
19 votes
6 answers
5k views

The falling broom handle

As the reaction to my previous physics puzzle was somewhat mixed, I'll try again. I found this in an online physics book. You hold a broom as shown in the following picture: The head of the broom is ...
Jaap Scherphuis's user avatar
18 votes
10 answers
2k views

Two many rainbows?

Wish I’d had a camera at the time but a cartoon will have to suffice, representing two actual incomplete rainbows that stop in midair where they meet, lit only by a setting sun. This seemed so ...
humn's user avatar
  • 21.9k
7 votes
2 answers
1k views

Don't put yourself out, dear

I asked my mother the other day, "What do you want for dinner? I'll get you anything your little heart desires." My mother, true to form, radiated the stereotypical motherly vibe: "Don't worry about ...
Chowzen's user avatar
  • 25.7k
7 votes
2 answers
459 views

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 ...
Riley's user avatar
  • 14.5k
6 votes
1 answer
463 views

Calculate total score from average score

A class of students have taken $8$ exams. The average scores of the exams are: 1st: $80.12$ 2nd: $74.59$ 3rd: $77.83$ 4th: $77.34$ 5th: $82.07$ 6th: $81.25$ 7th: $78.90$ 8th: $75.44$ What is the total ...
WhatsUp's user avatar
  • 7,407
4 votes
1 answer
156 views

Reconstructing sport climbing results

Sport climbing at the 2020 Summer Olympics – Women's combined Warmup Sport climbing is a new event (one of four) at the 2020 Summer Olympics in Tokyo, and it just finished. Two events were held, one ...
A. Rex's user avatar
  • 955
2 votes
1 answer
102 views

Can you produce a wolf's template? Part 2

Here is the first question. You are given a square piece of paper with no marks on it. With this paper, you have to make a wolf's template. You are given no tools such as a ruler or scissors, and all ...
Nick's user avatar
  • 1,695