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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.

1
vote
2answers
94 views

Unravel this simple cryptic Unique NUMBER relationship

Find GC ...it is a concatenated number Given: N + U + M + B + E + R = GC
8
votes
1answer
677 views

A B C in close knit relationship.. Who are they?

Find these closely knit numbers examining their relationships. A, B, C are distinct positive integers. AB, AC are concatenated Numbers. Given: 1 / AC = 0.0BC0BC0BC...... 1 / BC = 0.0AC0AC0AC......
9
votes
3answers
1k views

Find the area of the rectangle

The image below shows a half circle, and a rectange DBFE. Your task is simply to calculate the area of the rectangle, based on the information given in the image.
0
votes
1answer
98 views

Identify the rule and find the missing number

The following sets of numbers are connected through a common rule/patern. Find the missing number(?) $(255,153,51x)(153,0xx,51x) = 669900$ $(255,204,51x)(204,51x,51x) = 339900$ $(153,153,...
4
votes
1answer
203 views

Join the Fun at Jack’s Casino to get a shot at Jackpot

Jack’s casino dealers are not all prime. But, he gives better odds to get the daily Jackpot by revealing lot more numbers in the sequence in play. That way his Casino is much better than Cryptic ...
7
votes
1answer
352 views

It is as easy as A B C, Figure out U V C from the given relationship

Given $ U, V, C $ are three distinct digits, figure them out from the following relation: $$ \overline{CCC} = \overline{UVUVUV} \div \left ( \overline{UV} \times \overline{UV} \right) $$
0
votes
1answer
72 views

Find the missing parking space number [duplicate]

Each space in this parking area is numbered. The parked car covers one of the numbers. What is the number? For reference, the parking numbers are $16,06,68,88,X,98$ where $X$ is the hidden number.
2
votes
3answers
2k views

Should I take the antidote? [closed]

A new disease has been discovered in the world, it is called Blue. Statistically 1:1000 people in the world has it and it makes your whole skin blue in a few weeks after getting the disease but not ...
13
votes
5answers
2k views

Find the unknown area, x

The image below shows one large rectangle, with smaller rectangles inside it. Your task is simply to calculate the area of the red rectangle, marked with an x. Note that I have deliberately made the ...
3
votes
1answer
115 views

Find the first three terms of the sequence

Find the missing values in the sequence: $X, X, X, 59, 2, 65, 3, 58, 9, 79, 3, 23$ Hint 1: Hint 2:
1
vote
3answers
125 views

Find the next three terms in the sequence

This sequence consists of triplets; each triplet is linked to each other. $1,36,8,2,48,4,3,60,0,\text{X},\text{X},\text{X}$ The three $\text{X}$'s signify the missing numbers.
5
votes
1answer
133 views

Find the immediate square dancing neighbors, they dance together to perfect square

We live in a community of houses sequentially numbered from 1 to 100. We all love square dancing but only two immediate neighbors are joy to watch. If you concatenate their house numbers, it forms a ...
17
votes
2answers
2k views

We are two immediate neighbors who forged our own powers to form concatenated relationship. Who are we?

Our concatenated number is $ \overline{ABAC}, $ where $ A, B, C $ are all positive digits (1 - 9). Our relationship is $$ \overline{ABAC} = A^A + B^B + A^A + C^C $$ Who are we?
9
votes
1answer
602 views

Narcissistic cube asks who are we?

I am a five digit narcissistic cube who likes to display my root right upfront. I also have hidden it in the back of my four digit cube brother. Who are we?
6
votes
5answers
1k views

Long digital sequence. 16xxxxxxxxxxxxx61

Find the digital key and very simple method to unlock the long digital sequence 16xxxxxx61 Additional clues: Eeryday one clue will be given till problem is solved Day 1: Bounty Day 2: My code is ...
-9
votes
1answer
96 views

Number of days in a normal year expressed with five consecutive positive integers [closed]

Given $D$ is the total number of days in a normal year $a$, $b$ are positive integers $P$, $Q$, $R$, $S$, $T$ are consecutive integers Figure them out by combining the following six expressions ...
19
votes
6answers
2k views

My Sixteen Friendly Students

I have sixteen students in my class who sit in four rows of four. Each week they sit in a different order. After a number of weeks every student has sat next to every other student, next meaning ...
13
votes
3answers
2k views

99 coins into the sacks

You have 99 coins that you need to place into any number of sacks. After doing so, you write on each one the number of sacks that are lighter than that sack. For example, if you put 98 coins into one ...
-1
votes
2answers
158 views

Excellent Bike Riders. All under 100. Find the missing members marked x

Excellent Bike Riders. All under 100. Find the missing members marked x. They are all members of special club. 97 X 59 29 X 23 X 7 X
-1
votes
1answer
188 views

Can you find this abundant dad and his six prime sons?

We are six little prime brothers. All our ages add up to the age of our abundant and old dad who is obviously not in his prime. However, if you pair him up with either of the prime neighbors, they ...
1
vote
3answers
462 views

Solve for the Number in the number..square..cube relationship

Each letter stands for a distinct digit...no computer or calculator needed. Just pure logic and some mental multiplication. CUBE is a concatenated number and it is a cube. X denotes multiplication. (...
5
votes
1answer
127 views

Surviving the Zombie Apocalypse

It is the zombie apocalypse. Your car has limited fuel in it, and you will not be able to refill your tank once you run out. You are planning one final mission to gather supplies. You have identified ...
0
votes
1answer
127 views

He said yes..she said no..they went back and forth..they agreed to [closed]

To call it a Prime. S, N, O are 3 distinct digits that are to be determined by you so that their conclusion is right Full concatenated number: SNOSNOS
5
votes
2answers
647 views

Madam I m Adam..please don’t get mad..you will no longer be prime

Take away $ \overline{MAD} $ from $ \overline{MADMADAM} $ to make her prime. $ \overline{ADAM} $ is prime too if he does not get mad: $ \overline{MADADAM}. $ $ M, A, D $ are 3 distinct digits that ...
6
votes
1answer
206 views

XOR: Is it possible to get $a$ and $b$ if I have $a \oplus b$ and $a \times b$?

Intuitively I would say yes but I can't find a way to prove it. I tried with small values and bruteforcing shows that there seems to only be one solution given a distinct tuplet. For example $(1,72)$ ...
5
votes
2answers
192 views

SafeCracker #2 - The Mission Continues

Thanks to an alert StackE user, we were able to get the first safe open. Mission Details This next safe is in a former employee's house. He is gone for now, so we have no time to spare. We weren't ...
2
votes
1answer
85 views
10
votes
7answers
2k views

Missing Piece of Pie - Can you find it?

A piece is missing! What should it be?
0
votes
1answer
73 views

Place Your Bets 3 , last of the series

A harder sequence to figure out... What are the next 4 cards, including suits?
2
votes
1answer
83 views

Place Your Bets - in sequence, of course

Your Puzzle There is some sort of pattern in cards below. Simply figure out what the next card should be. Note: You cannot re-use a card already in play.
3
votes
2answers
83 views

A Wine Problem for Puzzlers [duplicate]

Simple Follow the instructions on the label. In case you the image is too small, Given three bottles: 8, 5 and 3 liters capacity, divide 8 liters in half (4 + 4 liters) with the minimum number of ...
-3
votes
1answer
228 views

Repeating decimal. 0.01234567901234

Express the repeating base-10 decimal number $ 0.0123456790123456790... $ as a fraction $ \dfrac{1}{x} $ in any base system up to hexadecimal such that $ x $ has a minimal number of only 0s and 1s.
4
votes
1answer
789 views

Number of seconds in 6 weeks

Using only 3 characters (any single digit or one of the following operators: $ +,\, -,\, \times,\, \div,\, ! $), construct an expression that evaluates to the number of seconds in 6 weeks.
0
votes
1answer
90 views

Why do I always lose? [duplicate]

As always, good luck! Sarah is really good at math. I mean, really good at math. Every now and then we play this game where we take turns picking random numbers between 1 and 10, and we add these ...
0
votes
17answers
5k views

I’ve officially counted to infinity! [closed]

Sarah called me today and explained that she had counted to infinity. I shrugged and said it was impossible. She said that since I didn’t believe her, she would do it again, and this time in only ten ...
7
votes
3answers
210 views

Groundhog Puzzle [duplicate]

A groundhog has made an infinite number of holes one metre apart in a straight line in both directions on an infinite plane. Every day it travels a fixed number of holes in one direction. A farmer ...
18
votes
5answers
857 views

Primes less than 100 in a 4 x 4 board

Place one of the digits (0 to 9) in each of the cells of a 4 x 4 board so that as many as possible of the 25 primes less than 100 divide at least one of 10 positive 4-digit numbers that can be read ...
6
votes
2answers
173 views

Just a Simple Number Crossword

I made a small number crossword for my mathletes club that I thought I'd share. It's not too hard, I think it's just right for a coffee break. Have fun! (Edit: No answer has a leading zero)
0
votes
1answer
127 views

How much did he pay for the car? [closed]

A man withdrew half the money that was in his bank account to buy a second-hand car, then sold the car two weeks later, receiving only three-quarters of the price he had paid for it. When he paid the ...
6
votes
1answer
194 views

What kind of puzzle this is?

I received this picture, and the sender told me that it means something?
4
votes
3answers
788 views

Scheduling based problem

Can you place these numbers into 5 rows of 4 such that each row totals 20? 1, 2, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 6, 6, 7, 8, 8, 8
-1
votes
15answers
5k views

What is ls Largest Number Formed by only moving two sticks in 508?

Tilting the Image is not allowed. You can cannot change order of digits. You cannot change the Size if Digits unless you are harry potter. You can increase or decrease space between digits though. ...
18
votes
9answers
1k views

One-one communication

5 people are standing in a circle - person A needs to tell his salary to person B, but none of the others should know A's salary. How is this possible, if every person only whispers to the person on ...
0
votes
2answers
97 views

Max pieces to cover a chess board [closed]

Number of individual chess pieces to cover all chess board
4
votes
6answers
2k views

Find 108 by using 3,4,6

Assemble a formula using the numbers $3$, $4$ and $6$ in any order to make 108. You may use the operations; $x + y$ $x - y$ $x \times y$ $x \div y$ $x!$ $\sqrt{x}$ $\sqrt[\leftroot{-2}\uproot{2}x]{...
4
votes
2answers
226 views

100 prisoners' names in boxes, against smart warden

My question, which I do not know the answer to, concerns the classic 100 prisoners and 100 boxes puzzle, summarized below. The solution to this assumes the names are placed in boxes randomly, and gets ...
0
votes
1answer
97 views

Arranging people in groups at a conference

54 people attend a conference. There are 6 tables that each seat 9 people. Each table has a different topic and all 54 people have to move around and sit at each table. Can you advise a formula as ...
-2
votes
2answers
145 views

All Unique Permutations [closed]

We have the word: RAPSEVNOBLURKANIWA We want to find the number of unique permutations that could be made with RAP always staying together, so that there are: no 3 adjacent consonants, ...
5
votes
2answers
150 views

Bracket schedule

my friends and I are doing beer Olympics. There are 12 teams with 6 games. Each game has its own “bracket”. Essentially there will be 6 winners, 1 from each bracket or game. Those teams will then ...
2
votes
1answer
322 views

Distance from One

For random natural number $N_0 > 1$, we find $N_1$ by the rule: $N_{i+1} = \frac{N_i}{2}$ if $N_i$ is even $N_{i+1} = 3N_i + 1$ if $N_i$ is odd If $N_1$ isn't equal to $1$, we find $...