# 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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### 4 identical shapes that touch each other?

It is known that one can have 4 shapes in a plane all touching each other, and not 5. You can add requirements to the 4 shape problem: Can you do it with 4 equal triangles? (No) Can you do it with 4 ...
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### Matchstick Puzzles

Puzzle #1: There is a matchstick: | Add 2 more matchsticks to make the number, 11. Puzzle #2: There is a palace made out of 11 matchsticks: Move 2 matchsticks to make 11 squares. Puzzle #3: ...
934 views

### Big number puzzle

I saw this on rec.puzzles many years ago, but can't find the reference to credit the source. I am thinking of a large number. If you want to multiply it by a two digit number $ab$ with $a \lt b$, ...
273 views

### Magic Race between Rabbit and Turtle - who will win?

The race is for 500km and these are the following items they can use in the magic race... Every defect will activate again after completing the mentioned time. Rabbit has the following items ...
547 views

### National Graph Lottery

In UK's National Lottery players choose 6 different whole numbers in the range 1 to 59, and win a large prize if all six match with the day's draw. Each choice of six numbers by a player gives rise ...
148 views

### What is a Dial Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Dial Word™. Use the ...
244 views

### Which is the missing number?

I am working on this puzzle since last week. 01 ?? 05 12 10 13 15 09 14 02 08 03 04 07 11 06 which is the missing number ?? note : answer is not 16
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Did you know that a prime, regardless of its base, is always a prime? I am looking for a prime. It’s the largest of its kind. In solving this puzzle, the answer you may find. ...
549 views

### Winning the Lottery

Bob: I hear you won the lottery. Alice: So I did! Bob: What six numbers did you win it with? Alice: Can't remember. All I recall is that they were all different, and none greater than 28. Bob: ...
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### Squares inside a square

Distribute the digits from 1 to 9 to a 3x3 square, such that you reach as many square numbers as possible. A valid square number in the 3x3 square is either a single digit square number or is build ...
504 views

### What is a NaturaW Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a NaturaW Word™. Use the ...
740 views

### What is a CirKle Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a CirKle Word™. Use the ...
2k views

### Many many thanks

The alphametic MANY + MANY = THANKS has no solutions in base 10. How many more "MANYs" must I add before it has a solution?
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### Greedy for Cash

Solve this Cryptarithm GIVE + MORE --------- MONEY Referenced from the Britannica Encyclopaedia No. 25 - "Number Prague"
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### 'The Imperial triangles' trigonometry question

There is a very well-known family of right triangles in Mathematics called "The Imperial triangles". Let me explain you how they are defined: We say $T_n$ is the $n$-th Imperial triangle if these two ...
389 views

### Minimum number of tries to find the balance!

There are 8 distinct weights and a two-pan equal arm balance scale, and you know the weights' weight order: the lightest is numbered as 1 and the heaviest is numbered as 8 and the rest accordingly. ...
16k views

### Get 100 as an answer on a calculator without using 0

Task Get 100 as an answer with only four keystrokes on a regular calculator. Disallowed keys 0 00 Allowed keys All other than the aforementioned two keys. Take the below image as a reference. ...
163 views

### Trying to figure a math puzzle/equation for a surprise trip using the date [closed]

I planning a surprise trip for my husband's 40th. He is a math geek. I am not. My plan is to tell him in a series of riddles/puzzles that he needs to figure out. We are going to LA to see his ...
193 views

### What are the house numbers?

Following the last question " What is the corner house number?" here is possibly a more challenging version. Fill in the missing house numbers on the map shown below. The area is occupied by math and ...
270 views

### map 5 unequal ranges to id

This is actually coming from a business place, but it's all about being able to do math tricks, and that's why I'm posting here. I want to implement the following function: ...
724 views

### Ernie and the Superconducting Boxes

I was in anticipation all last week. Ernie, who had been travelling for several months, was finally coming home. So over the weekend I dropped in on him. He was bursting with news. "Some wonderful ...
2k views

### A Magic Diamond

Place 15 different positive integers on the vertices of this graph so that the ten products of three numbers in a straight line are all equal.
169 views

### Hunting for treasure in 1-d grid [duplicate]

In a castle, there are N rooms in a line. Each room has a door to the two neighbouring rooms (or the one neighbouring room, for the rooms at either end). A treasure is hidden in one of the rooms. ...
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### Missing Piece of Pie - Can you find it?

A piece is missing! What should it be?
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### we are five we have three thousand four hundred fifty who are we? [closed]

we are five we three thousand four hundred fifty, who are we ?. Its a riddle like question but stranded with getting the answer for this question , am very sure the answer will make me slap my head ...
265 views

### 5 Precommitting Pirates Puzzle

Another variant of the Pirate Puzzle, inspired by this variant and a bit more complex. Scenario: Five pirates of different ages obtain 100 gold pieces in total, and want to decide how to split them. ...
Ten boxes are given with $a_1,a_2,a_3,a_4,a_5 ......a_{10}$ number of balls in them respectively .These boxes are randomly ordered but $a_1,a_2 .....a_{10}$ is told.We can arbitrary select a box and ...