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-4
votes
1answer
86 views

How to open the lock from this safe?

The puzzle is as follows: The figure from below shows a lock mechanism used to store sensitive data microfilms from a certain lab. This mechanism is magnetic and consists in numbered buttons which ...
-4
votes
0answers
62 views

How to get the least amount of pours to obtain a fractional amount of yoghurt?

The puzzle is as follows: A dairy plant in Milwaukee is well known for its yoghurt. However during the quality control a factory worker forgot to bring a set of adequate vessels to measure the ...
0
votes
2answers
92 views

What do these three towns have in common?

What do these three towns have in common? "Dublin", "Blackpool", "Chernobyl".
3
votes
2answers
435 views

How to fill 1/3 of the cylinder?

You are given 3 containers - pictured in this order below: a box with side 2, height 1, and a cone with base radius 1 and height 1 in the middle. a box with side 2, height 1, and a half sphere with ...
6
votes
1answer
180 views

I got [prefix] [suffix] [infix] from washing the [whole]

I got [prefix] [suffix] [infix] from washing the [whole]. P.S. I [infix] the [whole]. The note above, when the gaps are filled, will be a grammatical and reasonable note. What is the note?
4
votes
4answers
348 views

How to get the least number of flips to a plastic chips to get a certain figure?

The puzzle is as follows: (Transcription with grammar errors fixed) A game consists of the following: The challenge is to flip the chips in such a way so that they are as in state 2. You start in ...
6
votes
2answers
255 views

Pandigital fraction sum that evaluates to 1

Fill in the nine X spots in the following equation using each of 1, 2, ..., 9 exactly once, so that the equation is satisfied. The XX in the denominator denotes concatenation of two digits. $$ \frac{X}...
3
votes
2answers
353 views

In the sea or in the sky

In the sea or in the sky Sometimes also in your eye. Melancholy feels like me But energy I have plenty. Into me you have vanished Out of me you're astonished What am I?
-4
votes
2answers
66 views

A challenge to make 1 - 100 [closed]

So this challenge is you have (don't have to) make the numbers 1 - 100 by using the numbers 1, 3, 4, 6 only once. I'm stuck on how to make 54. Can anyone help me? P. S. You can use +, -, ÷, x, ! And ...
4
votes
2answers
1k views

Why is “HADAT” the solution to the crossword clue “went after”?

I was doing crossword from NY Times, from Mon, Feb 11, 2019 by Howard Barkin + Will Shortz and I got the following clue. Went after The answer is "HADAT". However, I can not find ...
37
votes
1answer
1k views

Didn't you ask me for a crossword?

An entry in Fortnightly Topic Challenge #forty-seven: "Wacky Sudokus" Here's that crossword you asked for... Sorry, what's that - you didn't ask me for a crossword?? TASK: Solve the puzzle ...
7
votes
2answers
252 views

Black board attack

How should Black move as to attack all the squares that have no piece on them with only ten legal moves for black? Any unoccupied squares must be attacked. Start from the position above as shown.
-2
votes
0answers
145 views

As seen in a dream

...
12
votes
1answer
362 views
+100

Skyscrapers in Sudoku!!! - SS#10

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the tenth puzzle in this series! For more information about the series, see the first ...
1
vote
1answer
111 views

How many 𝑛-digit integers have the property that the block of its first 𝑘 digits is a prime or divisible by 𝑘 for all 1 ≤ 𝑘 ≤ 𝑛?

Are there infinitely many integers with the property that the block of its first 𝑘 digits (for all 𝑘, 1 ≤ 𝑘 ≤ 𝑛, where 𝑛 is the number of its digits) is either a prime number or is divisible by 𝑘...
7
votes
1answer
175 views

Three to Seven in five or less

Can you change the word Three to the word Seven in five steps or less with the following rules: You must exactly replace two letters; one vowel and one consonant of the word in each step with a ...
7
votes
4answers
579 views

Divided by Pie Squared. Aaahhh

I have a machine that can divide a square pie into 9 equal square pieces using 4 blades: The blades can be moved, but there is only one control - which defines the width of the blades in both ...
2
votes
2answers
287 views

Four touching circles

Three identical circles are placed such that they touch each other. A larger circle is drawn around the smaller circles such that it touches them, as shown in the diagram. Can you find the ratio ...
5
votes
4answers
535 views

8x8 square with no adjacent numbers summing to a prime

Can you fill a 8x8 grid with numbers from 1 to 8 such that: Every number occurs exactly once in each row and in each column (Latin square). No two adjacent (horizontally or vertically) numbers sum to ...
2
votes
1answer
68 views

4x4 square with no increasing triples

Can you fill a 4x4 grid with numbers from 1 to 4 such that: Every number occurs exactly once in each row and in each column (Latin square). No row or column contains 3 adjacent numbers that are all ...
15
votes
1answer
459 views

Chain Puzzle: Video Games #01 - Teleporting Crosswords!

This is the first Chain Puzzle in the Video Games series, in which all puzzles are themed around video games of all genres. The answer to this puzzle is a thematic word or phrase. The solver whose ...
24
votes
1answer
1k views

A Puzzling Sudoku (Warning: Hot!)

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" A Sudoku with an oddly familiar shape. Here's a Penpa Link. Rules: Normal Sudoku rules apply (Special) Thermometers: The ...
9
votes
1answer
288 views

A 7x7 Suguru - SS#9

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the ninth puzzle in this series! For more information about the series, see the first ...
10
votes
1answer
345 views

Nurikabe: The Super-Kabe Attacks!

This puzzle is another Nurikabe, but with a new twist for me: it's a gigantic Super-Kabe! It's also, in my opinion, quite tricky and has some interesting deductions. I hope you enjoy! Rules of a ...
25
votes
1answer
1k views

The Blank Sudoku

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" (h/t to Beastly Gerbil, whose 1,2,3... Trinary!!! puzzle provided inspiration for this puzzle) This puzzle is a normal Sudoku, ...
20
votes
2answers
1k views

Not so random walk

I'm out for a very long walk, and I’m bored, so I decide to walk in a mathematical way. The first image shows the first 500 steps, and the second image is my path after 50000 steps. The colors are ...
11
votes
1answer
458 views

A Difficult Wacky Sudoku - SS#8

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the eighth puzzle in this series! For more information about the series, see the first ...
6
votes
3answers
650 views

I am thinking of a number

I am thinking of a number between 1 and 5000. It is the product of two primes. I tell my brother the larger of those primes, and to my sister the smaller. You are allowed to ask each of us questions, ...
-2
votes
4answers
319 views

My prefix, suffix and infix are right in front of you right now [closed]

My prefix, suffix and infix are right in front of you right now, displayed in this order: Suffix Prefix Infix What am I? Hint:
3
votes
2answers
177 views

I guess I'm French, tall and strong

I guess I'm French tall and strong. winds come and go, though they cannot blow me over. people buy me and sell me and I am very common on the street and roads but they rarely build me without help my ...
12
votes
1answer
223 views

A Scrumptious Sudoku Sandwich - SS#7

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the seventh puzzle in this series! For more information about the series, see the first ...
2
votes
1answer
57 views

A Conflicted Riley Riddle

My infix will give you a name My suffix will help you with pain My prefix will make you frown My whole will let you down What am I?
12
votes
1answer
324 views

Infinitely large, definitely cryptic

This is an infinite cryptic crossword. Solve the clues and use the four given grid pieces (each duplicated infinity times) to create a grid that continues endlessly in all directions. Across A1. ...
3
votes
1answer
114 views

My home is the air, the earth, and the sea

My home is the air, the earth, and the sea, Between highs and lows you are sure to find me. I am boisterous and loud, as bright as the sun, But those who can see me or hear me are none. I am born with ...
-3
votes
1answer
122 views

Add or subtract 212 in octal to get a palindrome

The puzzle is as follows: Suppose you have a three-digit number in the octal system. If you add or subtract 212 (also in the octal system) from that initial number, you get a three-digit palindromic ...
4
votes
2answers
124 views

⌈3n/2⌉−2 weighings are required to find the lightest and the heaviest coin among n coins. Prove/disprove this

We are given n coins, all of which have a different weight. Prove/disprove that ⌈3n/2⌉−2 weighings are required to find the heaviest and the lightest coins among them using a 2 pan balance scale. You ...
3
votes
3answers
152 views

Who is Mr. T and where does he work?

Part 1: Write each answer as ONEWORD, without spaces, punctuation or abbreviating. Some questions may have more than one answer when taken alone, but only certain answers will work with respect to the ...
2
votes
3answers
118 views

If I hold you and you hold me

If I hold you and you hold me, you might be alone. If I hold you and you don't hold me, someone could be following you. If I don't hold you but you hold me, you're very helpful. If neither of us holds ...
4
votes
1answer
144 views

Solving Kordemsky's Prime Cryptarithm and proving uniqueness

This is a cryptarithm from Kordemsky's The Moscow Puzzles, problem 273 to be precise. Each digit is a single-digit prime ($2,3,5,$ or $7$). Find a solution and prove that it is unique. $$\begin{array}{...
11
votes
1answer
273 views

Sudoku… with 10 digits? SS#6

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the sixth puzzle in this series! For more information about the series, see the first ...
13
votes
1answer
364 views

What is a Quotidian Word™?

This is in the spirit of the What is a Word™/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. It seems that it's a rite of passage on PSE to make at least one of ...
3
votes
1answer
221 views

A talk with Four Brothers

Once upon a time, on going to the small park nearby to take some fresh air, I met four quite peculiar brothers and had a talk with them. Each had a different story to tell. The first two brothers ...
7
votes
2answers
644 views

Are there any games like 0hh1 but with bigger grids?

I am loving 0hh1 but I got bored by the largest grid 12x12. Are there similar games but with much larger grids?
0
votes
0answers
88 views

First digit of 2021^2021 [duplicate]

Can you find the first digit of $2021^{2021}$ without a computer? Good luck!
18
votes
1answer
243 views

Compoundoku wants REALLY BIG and WACKY!

This is an entry for Fortnightly Topic Challenge #47: Wacky Sudokus. Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. ...
6
votes
1answer
422 views

Stop the robot by changing value of variable Z

You're a computer security expert (i.e a hacker who doesn't break law). Your neighbour is infamous professor MacGoofy himself. He specializes in designing programming languages and programming ...
10
votes
1answer
304 views

Nurikabe: The Twisty Corridors

This puzzle is a Nurikabe. It is a little tougher than my previous one, which was designed for newer solvers, and it has a particularly squiggly solution that I found pleasing enough to post - hence ...
6
votes
7answers
637 views

If you can walk

If you can walk, I'll point in the direction you need to walk. But only if you're close to me, otherwise I'll point in the opposite direction. If you can't walk, I'll point out what needs to change ...
7
votes
1answer
152 views

A Mosaic Sudoku - SS#5

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the fifth puzzle in this series! For more information about the series, see the first ...
5
votes
1answer
101 views

Interns & Errands

Going through the to-do list given to him by his bright-eyed boss, a wizard finds the following shopping list: a shaving of licorice root a red dragon's scale a lodestone and iron filings a drop of ...

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