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20 views

Numbers that are the sum of the cubes of their digits

There are just four 3-digit numbers which are the sums of the cubes of their digits. For example: 370 = 3^3 + 7^3 + 0^3 and 371 = 3^3 + 7^3 + 1^3. Without using a calculator/computer, can you ...
1
vote
1answer
18 views

Multiples of their reversals

8712 and 9801 are the only 4-digit numbers which are multiples of their reversals: 8712 = 4*2178 and 9801 = 9*1089. Without using a calculator/computer, can you find two 5-digit numbers with this ...
1
vote
2answers
54 views

Can someone solve this sudoku without trial and error? Please explain

Stuck in this sudoku. If anyone can solve this then please share the method.
4
votes
2answers
77 views

Find the missing shape

Here's a grid of shapes: Which of the following shapes should go in the missing cell, and why? There is only one correct answer, and the explanation should not be very complicated.
1
vote
0answers
46 views

Find the next number in the given sequence

I created this puzzle. Find the next number in the sequence and the logic behind it. $$2, 1536, 5, 1792, 23, 1184, 53, 1168, 113, 1048, 137, 1384, 179, 1576, 311, 1268, 431, 1234, 719, 2026, 1031, ...
5
votes
1answer
98 views

How can this puzzle be solved without guessing?

This puzzle was given to my 8 year old from the school. My child was struggling, so I gave it a bash, but was unable. I do sudoku regularly so know most methods of solving. I gave it to my husband and ...
0
votes
2answers
85 views

Assessment Centre Logic test

I have to exercises with solutions (red) from a german assesment centre logic test which I not understand: Does anybody the logic behind them?
2
votes
1answer
87 views

Find the equation of this surface - The Snowman

Here is a surface that resembles a snowman: Its equation has the form $f(x,y,z)=0$: if a point $(x,y,z)$ satisfies that equations it is shaded, otherwise it is "left blank". Your goal is to find $f$. ...
2
votes
1answer
59 views

How to understand this line in the solution to this puzzle?

I'm trying to understand the solution to a puzzle named "Expelled," the link to which is here. Most of the solution to the puzzle makes sense to me, except the most important part -- how to determine ...
9
votes
1answer
75 views

Cryptic Family Reunion: Unclaimed Ignition (Fan-Made)

Inspired by the Cryptic Family Reunion Series by Jeremy Dover. The answer to this puzzle is a list of seven thematically related words or proper names or phrases. Each of these is clued cryptically,...
0
votes
0answers
32 views

How do I solve this Vigenere puzzle? [closed]

I have tried vigenere cipher's decoders but they don't work. This is what it is: Wutg iyr rhw xosw qeonf, "yhrtrid no stmot shsindy gsyr." Can someone please help me?
9
votes
2answers
358 views

It's everywhere (yes, everywhere)

Here are 16 words which can be divided into 4 groups of 4 each. PLASMAS HUM EPIC BENZ OBSC MUND COND HIST GRAVEST CONS EXT CAROT ARC OVERT ...
11
votes
0answers
91 views

Alice and Bob invent a game

The rain was still falling in Wales, and Alice and Bob were terribly bored of having to stay inside the caravan. With just a deck of cards to entertain them they had played all of the card games in ...
0
votes
2answers
97 views

Triangular pool and three swimmers [closed]

Given a triangular pool 100, 120, 140 yards and three swimmers which swims at rates of 3.5, 4.0, 4.5 yards per second - place them on the edges of the pool in such way that when they start swimming at ...
3
votes
1answer
93 views

Phone pattern security

My phone is unlocked using a security pattern. This is a path drawn through a 3x3 grid of dots with the following rules: The path can start at any dot The path visits neighbouring dots: horizontally,...
6
votes
2answers
769 views

Wait, it is worth it?

You went to a Casino, and saw a quite interesting stall. The cardboard besides the stall says: You first pay \$$5$ You have to toss the fair coin. If it lands heads, you can ...
11
votes
2answers
103 views

Look at me - a number sequence

This sequence goes on forever, but here is the first 7 of them. The X's are just there to hide the actual digits. Can you find all the correct digits of the 8th entry? 1024, 90X1X, 25023X, 490364, ...
9
votes
2answers
303 views

Cryptic Exile by Sir Featherwait

Just the other day I met Sir Featherwait in the professional aviators' lounge, where he instructed me to guess his favorite anime. Unfortunately, it seems that every guess I made went further and ...
2
votes
2answers
84 views

stucked really bad with sudoku puzzle

Stuck with this for long time now, I have tried all the techniques yhat I know
3
votes
1answer
81 views

It's all in the 2's follow-up question

This is in regards to the solution in Slitherlink - It's all in the 2s I know it may seem dumb, but I don't understand the logic behind the second 2 chain in the solution. To help provide clarity ...
6
votes
1answer
81 views

Cryptic Family Reunion: Accentuate the Positive

The answer to this puzzle is a list of ten thematically related words or proper names or phrases. Each of these is clued cryptically, and the theme is to be determined. Since the definition part of a ...
3
votes
2answers
90 views

Tangential circles

The following figure has two axes of symmetry which define its width and length. The length (horizontal distance) is twice the width (vertical distance). The largest circle has a radius of 2005 and ...
9
votes
2answers
264 views

Probability of picking the red marble twice

Start with a bag containing one red marble and one white marble. Reach into the bag and pull out a marble at random. Put it back and do it again. If, on both times, you grabbed the red marble, stop. ...
22
votes
1answer
829 views

Hey, This is a 100th Puzzle of Mine!

Yep, this is my 100th puzzle here in PSE~ I'm really having a wonderful time here, thank you so much guys! >< I planned to write a harder and bigger one, but it turned out I was too lazy to do that....
10
votes
4answers
430 views

Floor functional equation

Find all functions $f:\mathbb{R}\to\mathbb{R}$ satisfying the following functional equation: $$f(\lfloor x\rfloor y)=f(x)\lfloor f(y)\rfloor\quad\quad\text{for all }x,y\in\mathbb{R},$$ where $\lfloor\...
9
votes
1answer
327 views

A functional equation again!

Determine all functions $f:\mathbb{R}\rightarrow\mathbb{R}$ such that $$(x-2)f(y)+f\big(y+2f(x)\big)=f\big(x+yf(x)\big)$$ for all $x,y\in\mathbb{R}$. Source: Math Excalibur Volume 22, Number 1 ...
9
votes
1answer
176 views

Mathematical golfing

You have probably heard of code golfing? There the task is to find the shortest computer program that produces the required output. Here we want to perform math golfing - find the shortest formula ...
5
votes
1answer
169 views

What's the puzzle?

Someone sent me a photo of the last few lines of a puzzle. They were: BULLDOZER OVENPROOF BROADTAIL BREAKER ASYNTACTIC TIFF ALKYNE ABOUND EVASIVE BEVERAGE HILARITY COOTIE What ...
9
votes
2answers
140 views

Cut It Up! (then find a phrase)

This is a "sorry for messing up yesterday's clues" puzzle. For each shape below, divide along grid-lines into identical pieces (rotation and reflection allowed). The first shape has 3 pieces, and the ...
4
votes
1answer
174 views
+300

Scrambler puzzle (CTF forensics problem by me!)

Before anyone starts hyperventilating, this is not part of an ongoing CTF! I just made this example CTF problem for fun... To learn more about what a CTF is, check out this Wikipedia page. For this ...
-1
votes
0answers
59 views

Deducing Puzzles [duplicate]

There are some puzzles , where it is very difficult to find the solutions and many will probably think that there are no solutions . But actually solutions are hidden as clues in the puzzles . Here ...
8
votes
1answer
259 views

120 degrees and circles

The bigger circle has a radius of $1$, and it is tangent to the two straight lines that forms an angle of $120$ degrees. The smaller circle is tangent to the two straight lines and the big circle. ...
4
votes
1answer
132 views

How to test a sudoku solver?

I have created a standard sudoku solver using my own algorithm. It relies on a continuous scanning with occasional tuple/pair searching. I am looking forward to test if this works properly. I have ...
7
votes
4answers
382 views

Take Two! (an Around-the-Bend)

Here's another around-the-bend. I felt like putting a hidden word in, but I couldn't think of anything good... there's still a word, though. Just unscramble the highlighted letters. Rules Each word ...
13
votes
3answers
922 views

Random walking on a board

There’s a pawn starting in the center of this game board. At each move, it can advance randomly towards any of the adjacent squares sharing a common side with equal chance. What’s the probability of ...
1
vote
1answer
157 views

A prolific nine-letter word

For the purpose of an arithmetical puzzle I am devising, I require a nine-letter legitimate (i.e. acceptable to Scrabble players) English word such that at least one permutation of all the letters of ...
3
votes
2answers
161 views

Hill cipher with 100x100 matrix?

Is it possible to decrypt/encrypt something using a Hill Cipher whose key matrix has a size of $100\times100$?
3
votes
1answer
87 views

Defeating the deleteriousness of time

What thing I'm talking about? Hint-1 Hint-2 Hint-3 Hint-4 Hint-5 (avoid)
9
votes
1answer
143 views

My First Riddle - What am I?

Amber, leather, fruit, or pine. Whiskey, crackers, never wine. White and red across a sea. Or clad twice in sable, burgundy. Hidden, swung, hooked, flown. Suited, bottled, jumping, thrown. You'll ...
13
votes
2answers
1k views

Triply English or Triply American

The following list of words divides evenly into two groups of words which I describe as Triply English and Triply American. American Assault Citation Common Count Diamond Fleet ...
9
votes
0answers
152 views

A fairy tale in a golden toy

Once upon a time, long long ago, in the days when good stories were far more beautiful and far harder to come by, a king was asked by his spoilt but beloved princess daughter to give her a fairy tale. ...
5
votes
3answers
330 views

Playing the Square Chess

On an ordinary chess board (8x8) without any pieces on it as a starting position, two players will alternately place a pawn on any square (unoccupied) so that the first player that form a square (...
5
votes
1answer
428 views

Everyone have me

Everyone have me; Without first two letters, I am not here; Without last two letters, I am a story; What am I?
37
votes
8answers
6k views

9-5=5? Matchstick problem

Move one matchstick to make an equality. Question made by me (Is this too easy?)
3
votes
3answers
131 views

Complete this cross sequence

What is the next element of this sequence and why? Possible choices: Hint
4
votes
1answer
157 views

Not to mean no-brainer

What does this picture mean? What are meant by different component of this picture? What is indicated by the square inside the red bevelle? Answer need to contain explanation. Ps. I made the ...
7
votes
1answer
179 views

Three squares in a triangle

In a triangle, three identical squares of side lengths 2.8 share a common vertex and are each touching two sides of the triangle. If one of the angles in the triangle is 75 degrees and is opposed to a ...
4
votes
1answer
240 views

Murder on the Fairway

A body has been found at the Green Estates Fairway. Next to the body was a bloody golf club which was later confirmed by the medical examiner to be the murder weapon. Thankfully, only ten men ...
3
votes
1answer
120 views

Raven Matrix-like tests

I have some Raven test that I couldn't find the answers Hope you can find the answers. I found this test in this IQ Test application.
7
votes
2answers
641 views

A Covid-19 puzzle: Alcohol for your School!

You are the principal of a primary school in HK. Schools are resuming soon, and you have to ensure that your school have enough alcohol. Each of the 30 classrooms should have a bottle containing 500mL ...

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