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Questions tagged [mathematics]

A puzzle strongly related to mathematical facts and objects, or whose solution needs serious mathematical arguments. General mathematics questions are off-topic but can be asked on Mathematics Stack Exchange.

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12
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5answers
3k views

Sequence Brain Teaser: Fill the gaps to create arithmetic sequences

Fill in each blank unshaded cell in the diagram below with a positive integer less than 100, such that every consecutive group of unshaded cells within a row or column is an arithmetic sequence. This ...
25
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3answers
3k views

What, the answer isn't the No of the Yes is?

Doorknob knows exactly how to solve this, so I ask him to not answer this question. Well, here's the puzzle: No, an answer is the cube without A, No? The Yes is No. The squared answer, Yes, is to an ...
4
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1answer
551 views

Check to see if a Configuration is Possible: prove there's an Hamiltonian path on a connected subset of the square grid graph

Alright, here's a new one for you guys. Instead of solving it, you need to determine if any given configuration is possible to solve, without actually solving it. It needs to be a general method of ...
31
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3answers
3k views

Cross-road optimization - what is the proper way to solve this type of puzzle?

This puzzle has 3 levels of increasing complexity. Each "level" is separate and complete, so feel free to post partial solutions to the individual levels only. I'm most interested in the principal ...
4
votes
1answer
433 views

Tune a podracer and choose the pilots by solving the podracer tuning equation

A long time ago, in a galaxy far, far away... These are troublesome times: The Galactic Republic is gone, the Jedis were exterminated due to order 66, Vader and Palpatine rules the galaxy with ...
16
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5answers
646 views

Secret within the Gossiping Partiers

Al and Jane are hosting a party tonight. Al plans on proposing to Jane, a secret only he knows. The party begins and all 8 guests arrive on time. Immediately and again every minute, everyone forms ...
1
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2answers
345 views

Magic Penteract!

(Don't worry, this is the last magic square themes question I'll be posting (as far as I know), so I picked a challenging one!) First off, let's define what a magic square is; A magic square is an ...
-5
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1answer
632 views

How Many Undefined Magic Constants are there?

Magic Square: An nxn square where every horizontal,vertical, and diagonal line all add up to the same number. Magic Constant: The number which every line with a magic square adds up to So most magic ...
9
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2answers
4k views

Does a magic rectangle exist?

My definition of a magic rectangle: Any $m \times n$ rectangle where $m \ne n$ and all the numbers $1, 2, 3,\dots, mn$ fit into the rectangle. All horizontal lines, vertical lines, and diagonal ...
3
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2answers
4k views

How to Determine a Magic Constant in a Magic Square?

A magic square consists of the numbers $1,2,\ldots,m^2$ placed into $m\times m$ square grid, so that every row, column, and both diagonals have the same sum. The magic constant of the square is this ...
2
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2answers
2k views

4D Maze Creation!

I have a problem for anybody who cares to try. You're job is to take a 10x10x10x10 size tesseract and design a maze that fits. The maze must be a perfect maze (no loops, one path cannot be followed ...
4
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2answers
747 views

How can we compute the 6 missing numbers?

There are 3 datatables. We forgot the numbers around the third square. How can we compute the 6 missing numbers?(there are question marks instead of them)
16
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3answers
3k views

A library with less information than one of its books

How can a library contain less information than one of the books in it? The library is intended to be a set of books on shelves. The information content is the least number of bits to describe the ...
3
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7answers
3k views

How many faces does this object have? [closed]

The object came with a few clues to help you figure it out. I can be viewed on paper I cannot be viewed in reality by your kind I am made up of what your mind can truly comprehend I resemble ...
30
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2answers
3k views

Determine the algorithm

So I was given this puzzle quite some time ago and just thought it would make a nice addition to this site: Your task is to determine the method how the result is determined from the given number. A ...
10
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1answer
873 views

An international affair: Find the common property in incorrect equations

Chaos at the international conference for world leaders: What should have been a peaceful exchange of ideas for common growth quickly exploded into hostility shortly after the German speaker addressed ...
7
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1answer
1k views

Oh no! Yet another number series… - Find the pattern in the two examples and provide an extension

Because these have been so successful in the past, I had to bring up my own. In fact, this puzzle was inspired by Find the next number even though I (and I guess everybody but the author) still don't ...
3
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4answers
1k views

Sell the fuel and become a Millionaire [duplicate]

You are living in the 22nd century. The fuel prices are unimaginably high and it is very rare to get, so the Government has introduced some new laws to control fuel smuggling. Rule 1: One cannot ...
20
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4answers
5k views

Hidden in plain sight - By what method do these images hide a prime number?

Note: This question has been severely edited from its original version to better fit the format of this site. Some answers below - including the accepted, correct answer - have been given based on the ...
7
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1answer
369 views

Wine with dinner

On a certain road there are 32 houses in a row, numbered 1 through 32, each inhabited by a single person. During the month of January each house is hosting a dinner date. House 1 on January 1, house ...
8
votes
1answer
2k views

Can you pass through the ancient tomb? Find the correct interpretation for the symbols

You have been crossing this hot and wet place for weeks now, but when you enter the cool and mouldy ruin, you know in seconds it has been worth it. Nobody has ever been here ( - well nobody in last ...
10
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5answers
1k views

Ernie and the Mystery of Madame Mu

Quite a few years ago (I can't remember the date but it was obviously some time after I first met Ernie at a New Years Eve party in 2001) I got an unexpected phone call late one afternoon. It was ...
12
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4answers
1k views

Random Walk on Ring City

Ring City has 100 houses arranged in a circle. Alice starts at her own house, and every day she randomly moves to one of the two adjacent houses, each with 50% probability. She repeats this until she ...
12
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1answer
698 views

Counting numbers with 3 dice

Yesterday I saw a pair of calendar dice that can be rotated and swapped to show all days of a month between 01 and 31. The dice have a digit painted on each face. First die: [0, 1, 2, 3, 4, 5] ...
8
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1answer
456 views

What is the meaning of a “tetrad twist” in Thistlethwaite's algorithm?

I am having difficulty understanding the third stage of Thistlethwaite's algorithm. I am using http://www.jaapsch.net/puzzles/thistle.htm. The third stage has a factor of [8!/(4!4!)]2 *2*3. This ...
5
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2answers
451 views

Continue this number-triplet series

(4-6-4) (6-12-8) (8-12-6) (12-30-20) What is the next number triplet - and why? I'll add hints if nobody gets the answer first. In the past I've used this riddle in a game with my RPG gaming group. ...
18
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8answers
2k views

When should you rest?

You are in an airport and are worried about missing your flight. So you start to run the long distance to the flight gate at a steady speed of 10km/h (you have bags and are not very fit). ...
2
votes
3answers
2k views

One to Nine Puzzle

I got those from a cereal box. You can use each number 1 to 9 only once. Operation should match the value in the green box horizonal and vertical My problem is Operation Order isnt specify in the ...
9
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4answers
937 views

Generalized Path Guards

Suppose you are traveling and come to a fork in the road. One of them leads to something good like a cat shelter and a company handing out free ice cream and money, while the other leads to something ...
32
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11answers
3k views

Coin weighing with a single weighing device

You have 12 coins which each weigh either 20 grams or 10 grams. Each is labelled from 1 to 12 so you can tell the coins apart. You have one weighing device as well. At each turn you can put as many ...
5
votes
3answers
476 views

Nerd on the Loose III - WHO, WHAT & WHY

Preface. After the extraordinarily easy "riddle", I guess I can wrap out everything in this "detective" puzzle. Background. Professor Swannie Taco is a genius in most fields of science and technology....
9
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1answer
1k views

Ernie and the Geometric Ginger Cookies

Ernie loves cooking and it's always worth the wait as he follows his curiously precise recipe to make Ginger Crunch Cookies. So I was happy to drop around when he invited me to help test his latest ...
12
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4answers
1k views

Nerds, Jocks, and Lockers

Here's an oldie but goodie from The Daily WTF; I paraphrase to avoid copyright issues: A middle school math teacher, who also happened to be the P.E. coach, made the following deal with the non-...
30
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16answers
6k views

Brothers, cousins, and foes - what am I?

I am one of many siblings in a great family. We are the most perfect of our race, Because each of us has a clear worst enemy. My foe - I know him well - is much like me, But we continually fight ...
30
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7answers
5k views

Dinosaur egg drop

Archeologists discover two dinosaur eggs, and you are given the chance to test the durability of these eggs (bad move on their part). Suppose that these eggs will absorb a specific amount of force ...
8
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2answers
337 views

Place the numbers

Consider the set of positive integers. Each integer can be definitively placed either above the line or below it. Given the initial collection of placements below, what are The next two numbers in ...
3
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2answers
443 views

Nerd on the Loose II - WHERE & HOW

Preface. Here is an relatively easy one, as compared to the previous part. We already found out when, let's find out where. Background. Professor Swannie Taco is a genius in most fields of science ...
31
votes
8answers
10k views

How many cars does the millionaire have?

I had a logical riddle on a programming interview test which was something like this: In his garage a millionaire had cars, of which only 2 were not white, only 2 were not green and only 2 were not ...
24
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16answers
4k views

The Golden Bird and The Ocean

The golden bird can only fly at 5 mph. That is the only way the bird can move. The bird must stop flying and rest its wings for 5 hours immediately after every hour of flying it does. That is the only ...
7
votes
4answers
939 views

Nerd on the Loose I - WHEN

Chat. I've created a chat room in case anyone wish to discuss this further. Preface. This is the first time I'm creating a puzzle. Since I find enjoyment in science and technology, the series of ...
2
votes
2answers
994 views

Determine the Maths Function [closed]

You found yourself in a weird room, there was no doors, but a limited computer with no internet that has open an app that is displaying the following message: f(0) = 0f(1) = 549f(2) = 646f(10) = ...
3
votes
1answer
1k views

Missing number in this sequence?

I heard this puzzle in a quiz I participated in: 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, ?, 100, 121, 10000 What is the missing number? (You don't need to do any big calculations, and you ...
18
votes
2answers
2k views

1 in, 1 out (The Security to the Party Maze)

A party is being held at a local mansion. The host is very rich and his success is because of one thing ~ his famous recipe for spaghetti! The spaghetti recipe is kept in a secret room inside the ...
12
votes
1answer
590 views

Measuring Lumberjacks

On average, a lumberjack is 10 logs taller (logs are usually measured in feet) than a normal person plus the height of his tan. Remember that most lumberjacks are young Canadians. Fill the blanks of ...
4
votes
1answer
503 views

The Security to the Party [Part 29]

A party is being held at a local mansion. The host is very rich and his success is because of one thing — his famous recipe for Spaghetti! The only guests that may attend are people who correctly ...
16
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2answers
1k views

Automatically a Knight, Knave, and Joker

Let M be a finite positive integer. It's exact value is not known. Suppose we have three classes of automaton, all of which accept a bit stream as input, produce a bit stream as output (one bit per ...
8
votes
3answers
1k views

A first choice die

You and your friend have met to play a game of dice. This is a very simple game where both players roll a die at the same time, and the player with the lower score pays a coin to the other player. In ...
11
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4answers
1k views

Optimization of area

You have a closed cord of length 100 meters which touches point $P$. There is a line $L$ whose closest point is 20 meters from point $P$. The value of a layout of cord is defined by the area ...
8
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2answers
413 views

The Security To The party [Part 23]

A party is being held at a local mansion. The host is very rich and his success is because of one thing ~ his famous recipe for Spaghetti! The only guests that may attend are people the host knows ...
34
votes
1answer
2k views

Cut the disk with a hole in four equal pieces

Cut the shape below in four congruent pieces. The gray area is a hole. In non-mathematical terms, cut the white area in 4 pieces having the same shape, same size, possibly mirrored or rotated. Note:...