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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.

2
votes
1answer
28 views

Finding a path on an n x n grid, top left corner to bottom right corner, where n is even?

Given a puzzle of the following form: Find a path between the top left corner to the bottom right corner, visiting each spot (.) exactly once. You can only move horizontally or vertically. ...
5
votes
2answers
148 views

Rotating 12 players on 2 tables

I'm stuck trying to find a good way to rotate 12 poker players on 2 tables. Assumptions: There are 12 players There are 2 tables We play for 4 hours Playing with sb means sitting at the same table ...
9
votes
0answers
218 views

Peaceful Encampments

This math puzzle is due to Donald Knuth (as far as I know; maybe he got it from someone else) circa 2014. Consider a plain represented by the unit square. On this plain we want to “peacefully ...
3
votes
1answer
118 views

need help in solving that numerical sequence

Sequence: 2, 3, ?, 8, 6, 7, 6, 5, 9, 3, ?, 1 I've tried to figure out what number I should replace to the *?*I have initially thought that was a modified fibonacci sequence example: we start with 2+3=...
7
votes
1answer
144 views

Three stubborn siblings

2560147913 Three stubborn siblings, of which only one is whole, making history is their goal. What word am I looking for?
1
vote
2answers
124 views

What is the secret of this Math(s) “joke”? [closed]

On a page called 14 jokes only intellectuals will really understand, it lists: A mathematician is heading to a house party. Just as he is coming up to the house, he notices there are no cars parked ...
9
votes
5answers
209 views

What's for dessert?

Another puzzle, yay! What do I want for dessert? An element, a blue liquid you breathe. The end of a sentence. wgpz tzggjr wgvxf bmzzi mzy It's three til' 4, plus forty more. Hint:
-4
votes
0answers
113 views

Numerical sequence

That's my last post for the week, I need help in solving this numerical sequence: ?, 36, 36, 18, 16, 14, ? I don't see any correlation between these numbers. Source:http://zagaza.ru/za548.htm ...
-4
votes
0answers
105 views

mathemathical-logical sequence solving

I need help in solving this sequence: 24, 333333, ?, ?, 53, 44444444, 82, ?, ?, 222244444444, ?, ?, ?, 444433333322221 reposting this because I wanted to add more informations. Now by taking a look ...
8
votes
8answers
987 views

What mysterious whole number am I?

From my second point of view I copy that amount of first. I am the dominant side of two but for many I'm the worst. I'll be tricky to find but today might be your day, after all my neighbour is 2/3 of ...
1
vote
1answer
133 views

Sequence solving

I need help to find the x: 6 3412 x 8605648 I've noticed that the end doubles everytime so we have 6 then 12, then we should have 24 then 48 , I have also noticed that the first 2 numbers ...
1
vote
2answers
145 views

Number sequence solving

Help me solving this sequence: need help 9,?,342,675,1230, ?,3561,5892 Source: http://zagaza.ru/za548.htm
5
votes
6answers
259 views

2019 to every day of the month

The grumpy professor looked at his class and said - ok so now it is 2019 can you use the four digits individually with *, +, -, /, ^ (raise to the power of) and ! to make each day of the month? You ...
13
votes
3answers
1k views

Spider and fly on a cube

A spider and a fly play a game with a cube of side length $s=1$ and with a positive real number $d$. First, the spider picks its starting point $S$ somewhere on the surface of the cube. Then the fly ...
1
vote
1answer
130 views

Solve this sequence -pattern

Ok,I need to find the solution to this sequence: 1.(09), 1.(4), 2, 3, ?, 17 the number in parentesis is an infinite decimal like 1,099999 or in the second one 1,4444444,but i can't find an answer for ...
7
votes
2answers
160 views

Which number goes in the square with the question mark?

My friend, who loves puzzles as much as me, gave me this image this afternoon. My friend game me a hint: Skyscraper, which, as Daniel Mathias pointed out in the comments, is a type of grid puzzle.
-5
votes
0answers
57 views

2,0,1,9 New Year Digit Game Number 51,52, and 98 [duplicate]

I found every sum from 1-100 using 2,0,1,9 except 51,52, and 98. Does anyone have the solutions? It would be greatly appreciated if you could share them. Rules: All four digits must be used in each ...
13
votes
2answers
693 views

Digit sums of successive integers

For a natural number $x$ both, the digit sum of $x$ and the digit sum of $x+1$ are multiples of $7$. What is the smallest possible $x$?
-2
votes
2answers
101 views

Make 'b' the subject in the quadratic formula [closed]

Solve for b in terms of a,x and c in the fastest way possible.
2
votes
2answers
346 views

Can the sum, difference and product of 2 numbers be perfect squares? [closed]

If we take 2 numbers $x$ and $y$ such that $x>y>0$ and , can $x + y$, $x - y$ and $xy$ all be perfect squares?
3
votes
2answers
75 views

Can you have the harmonic, geometric, arithmetic and quadratic mean of 2 numbers all being integers? [closed]

I created this problem looking at the hm-gm-am-qm inequality (hm = $\frac{2xy}{x + y}$, gm = $\sqrt{xy}$, am = $\frac{x + y}{2}$, qm = $\sqrt{\frac{x^2 + y^2}{2}}$ and hm $\le$ gm $\le$ am $\le$ qm). ...
10
votes
2answers
1k views

All neighbor sum is 0 on a chessboard

Neighbor cells of a matrix are defined as all the cells that share a common edge. A matrix is formed by putting real numbers in each cell. Form an $8 \times 8$ matrix (like a chessboard) where sum of ...
1
vote
2answers
96 views

Funny Business, Math Problem [closed]

The population of Humorville is 9,800 people. In this town, jokes travel fast. In one hour, each person who hears a joke tells three other people who have not heard it and tells no one else. Last ...
4
votes
1answer
198 views

This picture has some hidden message. What is it?

This picture was uploaded for the Olympiads of Medicine, from Porto. While the answer might be in portuguese, I don't find it likely. I tried some Caesar Cyphers, I assumed the colours represented ...
9
votes
1answer
298 views

The Lazy Laser Physicist: Part 2

The Lazy Laser Physicist is quite shocked about what happened to his setup over night: Almost all of his mirrors were taken away, but some other things have been put on his table. Besides these there ...
6
votes
4answers
318 views

Soar High for You? No Way!

Me and my fellows upon a time, Have earned the championship in our prime. Alas! That time has passed, my dearest fren', But we are still often used, according to Ben. Soar high for ...
10
votes
2answers
545 views

A differential equation with a hidden sentence

Find the specialized solution of $H''(r)-aH'(r)=0$ that satisfies $H'(0) = \frac{1}{p^2}$ and $H(0) = \frac{H'(0)}{a}(1+\frac{N}{Y}e^w)$ The question: Solve the above mathematic question Rewrite ...
2
votes
0answers
84 views

Write $\sqrt{5}$ as sums of powers of $1 + \sqrt{2}$? [closed]

The number $A = 1 + \sqrt{2}$ solve the equation $A^2 = 1 + 2 \sqrt{2} + 2 = 1+2A$. We also have that $$0 < \dots < A^{-2} < A^{-1} < 1 < A < A^2 < \dots $$ The powers are in ...
13
votes
3answers
648 views

Simple Maths Riddle 5

Here's a special one for you! I am prime, I am composite Sum my digits and half; I'll be perfect! Don't multiply them, I won't yield a thing But don't worry, it's only the beginning! ...
16
votes
1answer
475 views

To solve a simple heist

It happened by chance really. I was walking out from the bank when a man ran into me while rushing out. During our collision a piece of paper fell from his pocket. I quickly picked it up and tried ...
18
votes
2answers
2k views

A strange computer programming language

Here is a list of rational numbers: $\frac{22}{21}, \frac{7}{11}, \frac{13}{7}, \frac{51}{65}, \frac{13}{17}, \frac{1}{13}, \frac{15}{2}, \frac{7}{1}$ This list is actually a computer program! It ...
3
votes
3answers
1k views

Three coins for the fair king [duplicate]

Based on the question Eight coins for the fair king: I saw a comment saying "There isn't a good solution known even with three coins in all cases". So the challenge here is to try to solve the same ...
3
votes
1answer
122 views

Another variation of the game of Nim

Two players set several piles of chips. The piles are arranged in a row from left to right. By turns each player takes one chip from one of the piles and adds at will as many chips as he/she wishes (...
12
votes
4answers
592 views

A Chwistmas Widdle With a Twist

Chwistmas is the same with or without me, though I do wish you all Mewwy Chwistmas... I wish to be wid of my condition I am named and famed with humiliation A small happy square wheel! ...
3
votes
4answers
405 views

What will be the next term in this mathematical sequence?

What will be next in this series? $$0, 6, 24, 60, 120, 210, ...$$ I've tried it and noticed that the numbers are multiples of six. But I couldn't make a relation between them.
15
votes
2answers
374 views

What is the optimal strategy for this triangular board game?

I saw a board game somewhere and I want to know the optimal strategy for it. The game is played on a triangular board with 21 slots: The two players, red and blue, take turns to put numbered circles ...
2
votes
1answer
157 views

Help solving a math puzzle table

I am struggling to find the answer. Here is the source: math logic puzzle phone app.
45
votes
6answers
3k views

Eight coins for the fair king

You are responsible for creating new types of coins for the court. King respects the forgetful: he wants you to create 8 coins of different value, no more. King respects the feeble: he wants that any ...
2
votes
1answer
118 views

Just a little sum-thing

Select 5 numbers. Using exactly five copies of each, simultaneously create 15 (multi-)sets, one of each sum from 1 to 15 inclusive. Thanks to Gordon Hamilton for the inspiration...
0
votes
1answer
100 views

Who wins the game?

Two people play a game. The first one (A) picks one number from 1 to 10 and then the second one (B) also picks a number from 1 to 10 and adds it to the first number; the next round continues in the ...
0
votes
4answers
179 views

What is the missing number in the picture

interesting puzzle from facebook
5
votes
3answers
405 views

My Grandpa's Box #1

My grandpa died last month. At the reading of his will, he left me a strange wooden box. A post-it-note on the side read "You were always good at puzzles." There was a number lock on the front that ...
0
votes
2answers
108 views

Use all 10 digits to find the answer [closed]

Use all 10 digits to find the answer (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) _ _ _+ _ _ _= _ _ _ _
10
votes
1answer
2k views

Lost first game – can I still make my mother proud?

I am one of the greatest finger wrestlers of my generation. Only 0.1% of all players are better. When I play against someone who's worse than me, I win 99% of the time. Against someone who's ...
7
votes
1answer
476 views

What is the Unit Digit of the Sum?

I am thinking of 2 integers $x$ and $y$ which follow the following; $$2≤x≤y$$ $$x+y≤47$$ I then write the sum $S = x+y$ and the product $P=xy$ on two separate cards. I pass the sum card to player A ...
4
votes
3answers
361 views

Who is John's favourite painter?

John being his usual self forgot the name of his favourite painter. He went to the Oracle for assistance but inadvertently walked in on her while she was busy eating pie. Angry at the interruption, ...
4
votes
8answers
521 views

Finni's tricky game

Finni’s game: Person A thinks of a number (1 to 10). This number is called n. Person B says a number (1 to 10). This number is called x. Person A tells the absolute difference of n and x. This ...
4
votes
2answers
163 views

5 Digit Code Puzzle

We have a 5 digit code, any place can take 1 2 or 3. How do I find where the 2 is placed (if placed) knowing this criteria? 1) If the 1st digit is not a 3 then the 2nd is. 2) If the 1st ...
3
votes
1answer
107 views

How many possibilities are there for the buried treasure?

You have discovered a map to some buried treasure on an island the shape of a circle. The map has 9 markers which represent posts situated on the edges of the island. The 9 posts are located; North, ...
3
votes
2answers
110 views

Simple and intriguing

Five friends are sharing information about the marbles they have attempting to derive the total amount of marbles they own without disclosing to others the amount each own. They decide to do it by ...