# Questions tagged [mathematics]

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

4,778 questions
Filter by
Sorted by
Tagged with
198 views

### Keys and Locks Puzzle

Let $a,b,n$ be positive integers in which $a,b\le n$. You are locked in a room, with $n$ distinguishable keys and $n$ distinguishable locks in it. You know that each lock can be unlocked by a unique ...
• 5,710
82 views

### An elusive hotel guest [duplicate]

From Building Thinking Classrooms in Mathematics: An eccentric woman has booked three adjacent and adjoining hotel rooms. When she checks in, she tells the receptionist that if he needs her, she will ...
• 121
1 vote
184 views

### Solve the Alphametic: SOUNDS / WOW = ELK

This is a long-division problem in which letters are substituted for numbers. Solve the problem. Determine the number value of each letter; and when the letters in each one have been arranged in order ...
314 views

### Can we find four identically colored numbers?

Take the positive integers {1, 2, 3, ...} and color them red, green or blue. Is it true that no matter what coloring is chosen, we can always find three distinct numbers x, y and z so that x, y, z ...
• 11.7k
147 views

### Rubik's Cube with no two squares of the same color on any horizontal, vertical or diagonal line

Consider the 12 lines depicted below which all run through the centers of the 9 color squares of a single face of Rubik's Cube. Can you find a scramble such that on each line all squares have ...
• 1,699
126 views

### ORIGAMI: Above and beyond

It's been a long time since I've posted an origami puzzle! An origami puzzle is solved with some thickness $x$ iff it can be folded into a rectangle (possibly a square) with thickness $x$ everywhere. ...
• 3,165
1 vote
181 views

### find the 3 digits that calculate the same

Suzie was busy working in her office and helping compile Clayton’s expenses for which he has a daily elevenses allowance of less than £10 when she noticed that the three digits making up the amount of ...
• 11
222 views

### A "magical" grid progression

Task: fill in the final grid correctly. Hint, if it wasn't obvious enough already:
• 778
210 views

### Flipping DIP switches

About 30 years ago, I bought a memory extension card. At first, I was hesitating: there were 8 dip switches and no manual. Then the owner recalled that 4 switches indicated the memory on the ...
• 189
230 views

### origami SNY t28

It's been a long time since I've posted an origami puzzle! Fold the shape into a rectangle such that the rectangle is 28 layers thick everywhere. The purple part is the puzzle. Although solutions are ...
• 3,165
1 vote
332 views

### A simple cross-number puzzle # 2

Beginner puzzle This puzzle is intended to be suitable for people who are new to puzzle solving. Clarification: Both experienced solvers and new solvers are welcome to post solutions to this puzzle. ...
• 11.7k
2k views

### Shortest battleship game, to find the ships

This is a variant of this riddle. A (somewhat peculiar version of the) game of battleship, is played in the following way: The first player places as many ships as he wants on a very large N by N ...
• 275
1k views

### Making 1353 using Four fours

As the title says, the goal for this puzzle is making 1353 out of simply 4, 4, 4 and 4. Concatenation is not allowed. Here are all of the allowed operators. Addition (+), Subtraction and negatives (-)...
360 views

### Infinite Towers of Trouble (with a capital T that rhymes with P...)

Friends, we have a towering puzzle in which integers are equated to ordered pairs of colors. The ordered pairs are based on the nine colors given below: White, yellow, blue, red, violet, orange, green,...
• 821
224 views

### Visual puzzle involving mathematical operations

Try this puzzle. It involves mathematical operations. Created on my own. CSV (for those who aren't able to see images): ...
1k views

### Shortest battleship game, to find number of battleships

A (very peculiar version of the) game of battleship, is played in the following way: The first player places as many ships as he wants on a very large $N \times N$ board. Every ship is of width $1$, ...
• 275
895 views

### Gaps Between Ecuadorian Numbers

A positive integer is said to be an Ecuadorian number if for some m, the sum of the first m of its n digits, m < n, is equal to the sum of all its other digits. Numbers such as 11, 134, 235, 2024 ...
414 views

• 11.7k
379 views

### Tournament Scheduling Puzzle

I have an interesting real life problem that can be turned into an interesting puzzle pertaining to a tournament that can be represented in this way: I have 24 people which are assigned numbers 1 to ...
329 views

### Build a slanted pyramid with ten L-shaped blocks

Consider the following L-shaped 3-dimensional object made up of three unit cubes joined at their faces: Use 10 of the above L-shaped pieces to make the following shape:
• 11.7k
992 views

### Make a square table top with the minimal needed amount of straight cuts

inspired by : Make a square table top with six (or fewer) pieces A carpenter has three pieces of beautiful wood, measuring 12 inches, 15 inches, and 16 inches square, respectively. They want to use ...
• 9,218
173 views

### A pandigital alphametic

Find, as Ed Pegg did, at least one solution of this pandigital alphametic: A x BC x DEF = GHIJ. How many solutions does it have altogether? (...
395 views

### Dishonest dungeon staff

You are faced with the difficult task to set up a dungeon for adventurers. However you made a deal with the guild: any adventurer brave enough to beat the dungeon and reach the treasure room will be ...
• 1,182
499 views

### Make a square table top with six (or fewer) pieces

A man had three pieces of beautiful wood, measuring 12 inches, 15 inches, and 16 inches square respectively. He wanted to cut these into the fewest pieces possible that would fit together and form a ...
• 11.7k
1k views

### Professor Rackbrane: Count the triangles

Professor Rackbrane has just given me the following puzzle as an example of those that interested his party at Christmas. Draw a pentagon, and connect each point with every other point by straight ...
• 11.7k
233 views

### Ernie and the Kzijekistanian Coup

A couple of days ago I noticed an article in the International News section of our local newspaper headlined Kzijekistanian Empress Abdicates. Reading on, I discovered that she "… stepped down ...
• 14k
876 views

### How to solve this "Sum things to consider" puzzle? (AARP magazine, April/May 2024)

For context: I am not old enough to be receiving the AARP magazine, however both my parents receive it and I enjoy reading the AARP magazines. I have recently been reading the most recent AARP ...
• 2,379
1k views

### Fix the addition so that the sum is 1,111

111 333 555 777 + 999 ----- 1,111 The above addition is not correct. Can you fix it? For which numbers $n$ can you change $n$ of the $15$ digits of the ...
• 11.7k