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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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10
votes
2answers
538 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 ...
2
votes
1answer
145 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 ...
5
votes
0answers
228 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
9
votes
3answers
305 views

Know your primes

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. ...
8
votes
1answer
546 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: ...
15
votes
4answers
996 views

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 ...
14
votes
1answer
479 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 ...
16
votes
1answer
729 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 ...
14
votes
4answers
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?
6
votes
1answer
578 views

Which Numbers Replace the Question Marks?

Can you find out what the numbers below have in common? Can you figure out what comes next? ...
3
votes
2answers
152 views

Greedy for Cash

Solve this Cryptarithm GIVE + MORE --------- MONEY Referenced from the Britannica Encyclopaedia No. 25 - "Number Prague"
1
vote
2answers
435 views

'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 ...
8
votes
2answers
384 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. ...
23
votes
6answers
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. ...
3
votes
0answers
158 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 ...
7
votes
1answer
185 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 ...
5
votes
1answer
262 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: ...
12
votes
1answer
674 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 ...
11
votes
4answers
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.
0
votes
2answers
165 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. ...
14
votes
3answers
1k views

How many consecutive integers can you make using only four digits?

In the spirit of the classic four fours, I wonder what's the optimal set of four numbers? Your goal is to make the most consecutive integers using four digits of your choice. Pick four: $0,1,2,3,...
4
votes
2answers
302 views

By American Standards

I once went to the USA and a guy asked me, "What is a+B?" I could answer him. What was my answer? HINT: Note: The title is appropriate, and B is capitalized on purpose.
2
votes
2answers
152 views

Cyrus' Adventure (Part 5)

Cyrus walked through the third door and went into a damp passageway. Suddenly, Cyrus found a big bug on the floor. "Damn!" Cyrus stepped on it and the bug died. After a while, Cyrus arrived at a small ...
16
votes
1answer
891 views

Box of tablets, whole or broken: solution required

This is a puzzle that I thought up whilst taking a course of meds. I currently haven’t solved it, and would be curious to know if anyone has a solution for it. Here goes: Scenario: John has a box of ...
21
votes
10answers
111k views

Five Angles in a Star

In a regular pentagram (5-pointed star), the angle in each point is 36 degrees, so the angles in all five points sum to 180 degrees: What about an irregular pentagram, such as the following? Now the ...
2
votes
1answer
398 views

What's the missing number?

$\begin{array}{ccc}6&7&4\\ 4&11&14\\ 13&2&11\\ 6&8&1\\ 15&3&?\end{array}$ Own attempt at building a puzzle, find the missing number.
3
votes
1answer
213 views

Missing Number in a Seven Segment Circle

What number should replace the question mark? Please be helpful. If you have the answer, please reply to this post with the explanation and answer. If you don't have the answer, then don't comment. ...
2
votes
1answer
327 views

Master and Slave versus Bob: hard version

Continuation of: "Sub-puzzle: Master and Slave versus Bob the Violent but Honest Psychopath" and "Master and Slave versus Bob: easy version" The hard version is identical to the easy version (see ...
7
votes
2answers
303 views

Alice and Bob play at cards

To pass the time Alice and Bob play a simple game of chance where cards are drawn in pairs from a shuffled standard 52-card deck. If two red cards are drawn Alice wins the round. If two black cards ...
0
votes
1answer
108 views

What value will be replaced by question mark? [closed]

I can't find any answer The options are: (a)18. (B) 16. (C)10. (D)12!
3
votes
0answers
199 views

Find the missing element?

I've been trying to solve this for quite some time, can you help me solve it? This puzzle was made by one of my friend's teachers. This is not copyrighted and cannot be found anywhere on the internet. ...
-2
votes
2answers
180 views

I need a solution for this puzzle [closed]

This is meant to be a simple puzzle Given that: 3 - 4= -1 5 + 3= 7 2 + 6= 15 30 / 6= 20 Find: 20% of the sum for the final answer Hint: Final Answer Format: 00/0=0 (/ = ÷) (Divide Symbol)
11
votes
2answers
3k views

The grades of the students in a class

You are a new Math 102 professor in a university class of 88 students and would like to learn their grades from previous semester to know your students better and put a note of it to get an idea how ...
-9
votes
1answer
142 views

What number I am? [closed]

I am a 4 digit number The digit in the ones place is 6 The value of the digit in the hundreds places is 500 The digits in the tens and thousands places are the same and they add up to 8 What number I ...
12
votes
6answers
722 views

Use 0 1 2 3 4 to form 9 3-digit numbers

Use $0, 1, 2, 3, 4$ to make the any of these numbers: $$331, 333, 435, 452, 455, 458, 461, 469, 470$$ You must use all $5$ digits $0, 1, 2, 3, 4$ each exactly once. You can make multi-digit ...
10
votes
2answers
432 views

#, %O, and so on

I woke up this morning to find someone had added a new button to my basic calculator. Besides the $+$, $-$, $\times$ and $\div$ buttons, there's now also a $\#$ button. I figured, "Well, this probably ...
2
votes
1answer
213 views

How to solve the input output puzzle?

Here's the puzzle I am solving daily input-output challenge questions in the gradeup android app in order to take preparation for SBI (State Bank of India) PO (Probationary officer). Here I came ...
18
votes
3answers
5k views

You surely don't want to score 100/100

The Story: Today, the Maths quizzes are handed out by the teacher. You got 100/100. Everyone got 100/100. But you're not happy with it. Everyone's not happy with it. You want to ...
4
votes
1answer
353 views

Chess Massacre Variants-Play Find The Fastest Way?

I have thought up several variations of massacre chess. Massacre chess is a game where almost every single move is a capture. The idea here is that only the chosen type of piece can capture. It ...
2
votes
1answer
189 views

Four coins on my desk

I have four coins, all of which are United States currency, on my desk. Some of these coins are face up, and the rest are face down. I know the following facts about the four coins: 1) Each of the ...
5
votes
2answers
700 views

Legal advise for a family dilemma

"A client of mine," said a lawyer, "was on the point of death when his wife was about to present him with a child. I drew up his will, in which he settled two-thirds of his estate upon his son (if it ...
4
votes
1answer
116 views

The ultimate conversion of a square into right angle pyramid

This is a follow up of other puzzles. Here a general case of which the other cases are a subset. Given a square of any size, cut it into four pieces to be reassembled into a right angle pyramid (the ...
27
votes
5answers
4k views

An unusual and very hard number sequence problem

I heard this number sequence problem about 25 years ago from a maths lecturer. What number should go in the place of the question mark in this mathematical sequence: $..., 30, ?, 60, 90, 140, 225, ...
11
votes
7answers
2k views
-3
votes
1answer
510 views

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 ...
3
votes
2answers
255 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. ...
2
votes
0answers
83 views

Complete the series on this set of numbers [closed]

Here is one that I can't seem to solve: Complete the following series: 529, 531, 542, 544, 561, 558
1
vote
2answers
255 views

Minimize sum of guesses to win lottery

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 ...
8
votes
3answers
5k views

How to make 21?

How do you make $21$ from the numbers $1$, $5$, $6$, and $7$? You can use the operations of addition, subtraction, multiplication and division, as well as brackets. You must use each number exactly ...
5
votes
1answer
294 views

5 Negotiating Pirates Puzzle

5 pirates of different ages have a treasure of 100 gold coins. On their ship, they decide to split the coins using this scheme: The oldest pirate proposes how to share the coins, and ALL pirates (...