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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4answers
151 views

Go for the Gold

You are given a bag containing 1 and 2 ounce gold rounds. You need to draw one coin at a time till they Sum up to ten rounds. How many different ways you can achieve that? What is the quickest path ...
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6answers
635 views

Resulting number of vampires [closed]

A vampire enters a town and bites 2 person every night. The bitten 2 persons grow into two big vampires and combined bite 4 persons the next night. These 4 vampires combined bite 6 people the next ...
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1answer
150 views

Making 49 from 5, 1, 3, 4 [closed]

I have these numbers: 5, 1, 3, 4. There are four different ways to make 49 - what are they?
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2answers
765 views

Magic square using consecutive odd numbers -5 through 11

Using consecutive odd numbers from negative five to eleven, make a 3x3 magic square
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2answers
287 views

The four prisoners [closed]

Four prisoners, 1, 2, 3 and 4, are all condemned to death. One of them is at random selected to be pardoned. 1 asks the guard who will be executed. The guard refuses to tell him so instead 1 says '...
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1answer
2k views

Magic puzzle of numbers [duplicate]

Send the solution as fast as possible with the way of solving it
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1answer
86 views

Express 50 to 100 with constituent digits only…my 100th pzl on 50th day

Using the following rules only, Express the numbers from 50 to 100 using only digits in the number. Concise with minimum number of characters is preferred. No concatenation of numbers allowed. Only, ...
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1answer
104 views

Create numbers from 50-100 only using 1,2,3 and 5 [closed]

Create numbers from 50-100 only using 1,2,3 and 5. No repeats and you have to use each number. Also, you can use any operation! thanks :)?
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1answer
96 views

Fibonacci again..Distinct Digits..Detail all your Deductive Steps [closed]

$ABB$ $CDE$ $GFB$ $DPGB$ $QPFR$ $RDFD$
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1answer
180 views

Help me settle a bet between 2 friends [closed]

They were driving go carts a few months ago and now the topic came up that friend1 (who was first in race) overtook friend2 (who was second in the race), of course friend1 claims he overtook him and ...
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votes
2answers
109 views

Find the Smallest Value from these given digits [closed]

0 1 2 3 4 5 6 7 8 9 + - : x = Find the smallest value from these following numbers and equations. Each number and equations must be used once. You can make it like ...:(-1) Goodluck!
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1answer
100 views

Surprisingly(not literally) easy one? [closed]

What are the next two numbers in the following sequence: 0, 1, 4, 18, __, __. Please explain your logic.
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1answer
232 views

General Reasoning Puzzle About a Tank.? [duplicate]

A tank has been filled with water. On each minute advance the tank will fill double than previous. ie after completing one minute the tank will fill double the water as that in previous.So the tank ...
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1answer
242 views

Break the calculation for a dollar [duplicate]

3 friend went to a coffee shop. They ordered their coffee, had it and enjoyed their time. Waiter came with a bill of \$30. So they decided to pay \$10 each. Waiter gave them \$5 in return as a ...
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1answer
613 views

How Many Undefined Magic Constants are there?

Magic Square: An nxn square where every horizontal,vertical, and diagonal line all add up to the same number. Magic Constant: The number which every line with a magic square adds up to So most magic ...
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1answer
59 views

Next number in the following sequence [closed]

1, 2, 3, 5, 8, 13, 21, and so on. Find the next digit.
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2answers
82 views

MATH PUZZLE ABOUT SEQUENCE [closed]

In the array of numbers below, each number above the bottom row is equal to three times the number immediately below it. What is the value of x+y? ...
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1answer
77 views

What is the pattern that describes these numbers? [closed]

Supposed you are given the following numbers: 6 28 496 8128 33550336 8589869056 What's the relation between them?
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2answers
122 views

Deriving formulae? [closed]

Express 203 as a sum of four terms which are in a Geometric Progression. Then what is the common ratio ? Hence, there by arrive at a common formula for deriving four numbers which are in a G.P. Hint ...
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1answer
804 views

Squares splitting into 4 congruent shapes [closed]

how many ways can you divide a square into four congruent shapes? Remember that the answer cannot be infinity because rotations of one pattern still result in the same four congruent shapes.
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votes
1answer
215 views

What number am I thinking of? [closed]

Adding an odd number would make an even number. It's not the largest prime number. But when you divide it into parts I make a multiple of 2. the range never exceeded 100 but never to less from 30. ...
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votes
3answers
225 views

From the given Square - Factorial Relationship, deduce the unknowns

$Given$: A, B, C, D are distinct digits and can vary from 1 to 9. DB is a concatenated number. From the following relationship, solve for A,B,C,D. Give your deductive reasoning. Please read all ...
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2answers
135 views

Numberless Sudoku with Just a Letter and Symbol Combination

A Standard 9x9 Sudoku uses the digits 1 to 9. You are only allowed to use a single letter(say T) and a symbol of your choice to represent the digits 1 to 9. Rules should be well defined and the ...
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3answers
932 views

When Math Loses Meaning

In an alternative universe where the following is true: 1 # 1 = 3 2 # 2 = 7 1 # 2 = 5 What would ? be? 5 # 5 = ? YOU DO NOT NEED THE FOLLOWING TO FINISH. Extra equations:
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2answers
166 views

mensateaser [level 0] (part 1)

What should be the value of the bottom row in our Euro 2012 Football themed grid?
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3answers
575 views

A (Simple) Arithmetic puzzle

I'm hoping this one was not posted here already, tried to search a bit and didn't find it. It's a really nice brain teaser: Add arithmetic operators (plus, minus, times, divide) to make the ...
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4answers
199 views

Find 25 using 6, 25, 9, 8 only

You can only use these numbers once, so not square root or cubed root or anything else. Good Luck!!
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5answers
224 views

1 and 2 is 12 , 2 and 3 is 46 then what's 3 and 4? it's not 102 [closed]

How can these equations be true? one and two equals twelve two and three equals forty six Then what's three and four? (It's not 102)
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1answer
178 views

Find the radius

Information : AB = 8 CD = 7 O,B,D are centers of the respective circles Hint: Find hidden information/clue from the diagram to solve the puzzle. Note: diagram is not to scale; it is just for visual ...
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2answers
278 views

A math puzzle… what is the solution?

I have some addition problems to show you... 15 + 37 = 16 24 + 56 = 7 35 + 64 = 18 43 + 123 = 3 81 + 251 = n Based on the answers I've already given you, can you figure out the value of n?
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1answer
559 views

Trick-Or-Treat Probability Puzzle [closed]

On Halloween night, a young boy was trick-or-treating. It was late at night and he was on his last stop. He knocked at the door and said: Trick-or-Treat! The man inside said he had a bag of just 4 ...
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votes
2answers
3k views

Make numbers 33-100 using only digits 2,0,1,8

Use the numbers 2, 0, 1, and 8 (ALL of them...only ONE time each) to make every integer from 33 to 100. Allowed operations: +, -, x, ÷, ! (factorial), exponentiation, square root and Parentheses No ...
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votes
1answer
709 views

What's My Number (Math Riddle) [closed]

I am thinking of a number. I multiplied by 3, subtracted by 8, doubled the result, and added 14. Then i added on 50% of what I had and subtracted 11. Then i divided by 5. After all that, I was left ...
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votes
1answer
2k views

Mathemetic series 1, 3, 6, 10, 15, 21, 28, 36, 45,__? [closed]

I currently looking what will be the next value to 45 as per given series. Is there any specific equation available?
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1answer
255 views

The Missing Dollar [duplicate]

3 men walk into a restaurant with 25 coins each and order food. The bill is 72 coins. The 3 men pay their 25 coins each to the waiter and ask him to return quickly with the 3 coins change. The ...
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votes
1answer
116 views

The number of images of the point is.? [closed]

Two plane mirrors facing each other are arranged at $60^o$ to each other. A point is located on the angle bisector. How many images of the point are there?
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1answer
261 views

The Puzzling Phone [closed]

The amazing "Puzzling Phone", comes in two models, one sold by "Super Puzzling Inc", and one sold by "Mega Puzzling Ltd" Phones need to have government testing before they can be sold on the market. ...
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5answers
227 views

Find The Radius Of All The Circles

Find the diameters of all the circles shown, given the information provided in the diagram below. All diameters are of integer length. P.S: the signature in the bottom right is mine and I own this.
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3answers
944 views

The barber paradox - Who shaves the barber? [closed]

All the men in a village either shave themselves or are shaved by a barber (himself a man from the village). The barber claims to shave only the male villagers who do not shave themselves. So who ...
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votes
1answer
123 views

2 sets of 3 cards, 5 known cards, 1 unknown - What is the unknown card? [closed]

There are two sets. The last card of the second is unknown. The first set is 5, 6, and 10. The second set is 7, 2, and ? What card is the question mark hiding? I'm too awful at math to figure it out ...
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votes
2answers
450 views

Variation of an ant on a rubber rope problem

Original Problem: An ant starts from a rope of length 1m and with a speed of 0.1m/sec and simultaneous rope expands at a rate 1m/sec. If we find the ratio of end points to ant's position we get a ...
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votes
1answer
255 views

Filling a bucket of water with pi litres

There are 2 buckets- one has a volume of 4 litres and the other of 3 litres. You can fill the buckets with water and pour it out as you wish. Your goal is to have exactly 22/7 litres of water (pi ...
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1answer
656 views

Seven digit number

A number has seven digits. The product of the first three digits is equal to the product of the last three digits is equal to the product of the middle three digits. The digits are distinct. What is ...
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7answers
30k views

Make 24 With 7,3,7,3

You may use math signs you wish, but you must use the numbers 7,3,7,3 in an equation so it equals 24 Is it possible? If so, show how. No-nos: You are not allowed to combine numbers to make ...
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2answers
344 views

Absurd Equation

$37$ $12$ $9$ $×$ $2.5$ $÷$ $+$ $=$ $X$ Solve for $X$ Hint 1 Hint 2
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2answers
203 views

You have 6 burning candles [closed]

What's the answer for this question: You have 6 burning candles, and blow out two of them. How many candles are left standing after 24 hours? How do you know?
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6answers
255 views

Average of a Series

The "average" of a series is x. A new data point comes in with the value x + 1. But the new average is less than ...
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2answers
7k views

how many times 12 men may shake hands? [closed]

12 man participate in work Recruitment Service. Each participant saw every other participant and shook his hand. How many handshakes took place?
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1answer
371 views

Fraction Puzzle [closed]

I am a fraction. If you multiply me by two, the sum of me is 54. When you divide my numerator by 4, you get 6. When you divide my denominator by 6, you get 5. What decimal am I?
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1answer
1k views

Coins, Dice, and Probability! [closed]

Background: It's time for a little bit of fun, your friends are playing a game and you decide to join them! Gamplay: You each sit down and play on a flat surface. You sit in a circle and each throw ...