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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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330 views

### Find the element that does not fit the pattern

These 12 elements form a set with a certain pattern, but there is one element that does not fit. Which one is that? HINT
100 views

### On which day the pond will fill half? [duplicate]

A pond has flowers in it each day the flowers in the pond get doubled if the pond gets full-on 20th day, on which day the pond will fill half? How? We are sitting here in the office in a group and ...
175 views

### 10x10 divided into the most number of rectangles of different area

How can a 10x10 be divided into rectangles such that there are as many as possible and they all have different area? Can you find multiple solutions that are not mirror/rotation of each other? Good ...
658 views

### Guesstimate the number of windows in the Burj Khalifa

Guesstimate the number of windows in the Burj Khalifa How should I proceed while solving this question?
2k views

### Covering an 8x8 grid with X pentominoes

What is the minimum number of X pentominoes you need to cover every cell of an 8x8 grid? Pentominoes may overlap each other and sit outside the boundary of the grid. An X pentomino looks like this:
675 views

### Paint numbers from 1 to 23 with three colours

Can you paint every number from 1 to 23 with three colours, such that there are no distinct numbers $𝑎,𝑏,𝑐$ of the same colour with $𝑎+𝑏=𝑐$? For example, you cannot have 2, 3 and 5 of the same ...
182 views

### Identify the odd one out element

There are two columns (two sets), in each set there is a pattern among the 7 elements. The elements are not arranged in any order, the two patterns are not necessarily the same, but they are related ...
385 views

### Paint numbers from 1 to 8 with two colours

Can you paint every number from 1 to 8 with two colours, such that there are no distinct numbers $a, b, c$ of the same colour with $a+b=c$? For example, you cannot have 2, 3 and 5 of the same colour ...
95 views

### Last Person Remaining Avoids Death [duplicate]

There are 1600 people sitting around a circular table. The first person (person 1) has a sword and kills the second person then hands it to the next alive person (in this case person 3). Person 3 ...
627 views

### Number Equation Matrix

Can somebody please solve this? My daughter's school teacher gave her this puzzle to solve at home. But to me it seems a little out of order, and that's why I am asking here for help.
673 views

### Sharing cake among 9 or fewer people

You are expecting guests to your birthday party. You know that there will be at most 8 guests, but you don't know how many will actually come. What is the smallest number of pieces you should divide ...
154 views

### Covering an 8x8 grid with W pentominoes

What is the minimum number of W pentominoes you need to cover every cell of an 8x8 grid? Pentominoes may overlap each other and sit outside the boundary of the grid. They can also be rotated in any ...
120 views

### Rectangles formed from every tetromino, tromino and domino

Can you form a 4x7 rectangle from every tetromino, tromino and domino? There are 5 different tetrominoes, 2 trominoes and 1 domino. Can you find different arrangements that are not mirrors/rotations ...
109 views

### Can you solve it..it's very specious to me.please [closed]

. important... please sovle .....................
182 views

### A town E miles away?

I got this from my maths teacher What is the value of 'E'?
1k views

### Find d this ones stumped me help?

This one is annoying me so much. Got this from a maths teacher.
356 views

### 8x8 grid with no unpainted pentominoes

What is the smallest number of cells you need to paint in an 8x8 grid, such that it contains no unpainted pentominoes? Can you find multiple solutions? Note that a pentomino is a set of 5 adjacent ...
73 views

### 4x7 rectangle divided into 7 different rectangles

Can you divide a 4x7 rectangle into 7 rectangles all of different area? Can you find multiple solutions? Good luck! P.S. @Deusovi wanted me to make puzzles that have an "aha moment", so here is my ...
470 views

### 10x10 grid with no unpainted hexominoes

What is the smallest number of cells you need to paint in an 10x10 grid, such that it contains no unpainted hexominoes? Note that a hexomino is a set of 6 adjacent cells (horizontally or vertically). ...
139 views

### Prime magic star

Can you replace the letters with 10 consecutive primes such that the sum of numbers on each line is equal? I expect this to be solved with a computer. Good luck!
68 views

### Find numbers 30-50 using numbers 2,0,1,9 only, with PREMDAS [duplicate]

You can only use numbers 2, 0, 1, 9, but they do not need to be in order. You can only use the numbers once unless they are used again as an exponent. You can only use subtraction, addition, ...
50 views

### 7x13 rectangle divided into 13 different rectangles

Can you divide a 7x13 rectangle into 13 rectangles all of different area? Can you find multiple solutions? Note that rotations and mirrors don't count as separate solutions. Here is a similar puzzle ...
147 views

### Partition a 3x3 square into rectangles [closed]

Yesterday I watched "The man who knew infinity" about the amazing Ramanujan. Inspired by the partitions problem from the movie I came up with a puzzle: In how many ways can you partition a 3x3 grid ...
915 views

### Transferring 9 pegs on a 9x9 grid

You are given a 9x9 grid with a set of 9 pegs (red circles) arranged in a 3x3 pattern in the corner, as shown below: A peg can jump over another adjacent peg in any direction (horizontal, vertical or ...
198 views

### Rawrdon Mamsay pays a visit

Now, I should warn you, this is one of my practical problems; meaning I don't know the solution and the answer's probably anticlimactic (like this or that). Still... My old pal Rawrdon Mamsay is soon ...
638 views

### A curious 5x5 square

Can you fill a 5x5 grid with numbers from 1 to 5, such that every number occurs exactly once in each row, exactly once in each column and exactly once in each broken diagonal (in both directions)? ...
92 views

### Painting edges of a 3x3 grid with 4 colours

Can you paint the edges of a 3x3 grid with 4 colours, such that: The colours of edges of every 1x1 square are different. The colours of edges adjacent to every vertex are different. Here is a ...
60 views

### Painting edges of a 2x2 grid with 4 colours

Can you paint the edges of a 2x2 grid with 4 colours, such that: The colours of edges of every 1x1 square are different. The colours of edges adjacent to every vertex are different. Good luck!
46k views

### A camel transporting bananas

A somewhat well-known puzzle is described as such: You have a pile of 3,000 bananas. You wish to transport them to a place 1,000 miles away on the back of a camel; however, the camel can only carry ...
2k views

### Make 38, 44, 46 using 2,3,8,7?

Using BODMAS/BIDMAS* and the numbers and signs 2,3,7,8, (), -,+,÷,× can you make 38, 44, 46. You can only use each number once. I can't figure it out myself Brackets Order Division Multiply Add ...
123 views

### The Flippin' Magician's 7-card Grand Finale

This question is a followup to this question by @ais523, which itself was a followup to this question by @Wen1now. After touring the globe to accolades when performing his 10-card trick and 8-card ...
1k views

### Haselbauer-Dickheiser Test no. 3: Circle divided by lines between a blue dots

This is the test no. 3 from Haselbauer-Dickheiser Test. 3. These three circles below all have blue dots on their circumference which are connected by straight lines. These lines divide the ...
168 views

### Cross the pond, but there's a catch!

There is a square pond, conveniently divided into segments, with coordinate $(0,0)$ in the bottom left and $(10,10)$ is the top right. You have planks length $2$ and $3$. You start at $(0,0)$ and ...
341 views

### Fill the Image Sequence Ep. 2

Suggested by Athin, try & make another feasible puzzle for this series. Enjoy :D The prologue also be revised more precisely. This puzzle will provide several images. These images compose a ...
6k views

### I'm largest when I'm five, what am I?

I'm very common and often you see me, Everything's believed to be made of me. Make no mistake, I look largest when I'm seven, But I'm largest when I'm five, it is proven. But alas at ...
2k views

### Consecutive numbers that are Manhattan distance 3 apart

Can you place numbers from 1 to 16 on a 4x4 grid, such that the distance between any two consecutive numbers ($a$ and $a+1$) is Manhattan distance 3? Bonus question: can you also make 1 and 16 be ...
218 views

### Primes from arithmetic and geometric progressions

The five primes, 131, 157, 211, 349, 739, are neither in arithmetic or geometric progression, but are instead the sum of the corresponding terms of two progressions of five terms each, one arithmetic ...
298 views

### Consecutive numbers that are Manhattan distance 5 apart

Can you place numbers from 1 to 36 on a 6x6 grid, such that the distance between any two consecutive numbers ($a$ and $a+1$) is Manhattan distance 5? Bonus question: can you also make 1 and 36 be ...
242 views

### computer programmer's maths puzzle [closed]

A computer programmer looked at part of his code x = x + 1; and then thought what a strange equation that would be for a mathematician $$x=x+1$$ The programmer ...
266 views

### It's his birthday!

A friend of mine told me that he was about to have his birthday. However, he didn't tell me what his birthday was. When is his birthday? Compulsory Hint 0 Compulsory Hint 1
140 views

### Painting a 6x6 with 3 colours

Can you paint a 6x6 grid in red, green and blue, such that its every 3x3 sub-grid contains exactly 5 red, 3 green and 1 blue cell? Good luck!
1k views

### 3x3 self-descriptive squares

A self-descriptive square is a square grid filled with integers such that: The sum of the numbers in any row describes the number of times that row’s rightmost number appears in the square. The sum ...
1k views

### Generating Roman numerals with dice

This puzzle is closely based on this one: Generating numbers with cubes Now we want to generate Roman numerals by placing up to three 6-sided dice side by side. We are allowed to write multiple ...
465 views

### No interest ever. Just a fee for my end,

Need to lend a tenner? No interest ever. Just a fee for my end, A third of what I lend. Falling short of the fee? I will lend it to thee! What do I lend you all together?
191 views

### ARG Puzzle Gate 15 Help

Me and my group (yes I'm in a group trying to solve this) are currently working on an ARG puzzle and we are stuck. The first image/clue to the entire puzzle is what is seen below. The creator of this ...
509 views

### Paint 7 cells of a 7x7 grid

Can you paint 7 cells of a 7x7 grid such that the largest unpainted rectangle has area of 6 cells? Good luck!
1k views

### Generating numbers with cubes

I saw an interesting calendar in a shop. It is composed of two cubes with numbers written on their 6 sides. By placing these cubes side by side one can make any day of the month from 1 to 31 (even 32)....
75 views

### What are my sisters' ages? (With ice cream!) [duplicate]

This is from a book I read as a child. Steve said to his friend Jessica, "I have 3 sisters. The sum of their ages is the same as my age, and the product of their ages is 36. How old are my sisters?"...