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.

2,556 questions
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Why is this Simple Puzzle impossible to solve?

Connect each red circle with each black circle by drawing a line and the lines should not touch. From each red circle, 3 lines must be drawn which connect red circles with black circles, but the lines ...
135 views

Normal Knight sees the Big Picture during his Countrywide Travels [duplicate]

Normal Knight is savvy, energy saving as he travels through Regular Country... Ride along and Document Details of his Journey As this Knight (only chess move allowed) journeys through , he takes ...
358 views

How many possible starting positions are uniquely solvable for a nonogram puzzle?

This type of puzzle goes by many names: Nonogram, Picross, and Griddlers are all mentioned on the Wikipedia page, Simon Tatham calls it Pattern, I was introduced to it as Descartes Rainbow, ... The ...
110 views

Magical Knight Moves with Effortless Ease in his Magical Kingdom

Magical Knight knows every Square of his Magical Kingdom. In many respects, he is like any other knight...Literary,Prime, Normal(makes same allowed chess moves). He is people Knight . As he traverses ...
421 views

10 coins, 3 of them are fake

Inspired by some great weighing puzzles here (This being one of my favorites), I just made another weighing puzzle - I'm not quite sure how difficult or easy this one is. You are given 10 coins, 7 of ...
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Too early in the morning to have SODA?

Each letter shown represent distinct digit...can vary from zero to nine. $COCA$, $COLA$, $SODA$ are three concatenated numbers. Figure these out from the following relation: $COCA + COLA = SODA$
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Which number replace question mark [duplicate]

Answer my question that which number will replace question mark.
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-4 to 3 magic square [on hold]

Write the numbers -4 ,-3 ,-2,-1,0,1,2,3 in correct place value so that each of the square adds up to 0 Please solve this question, because I have tried this this question many times without success. ...
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What is the missing item in the following number pattern?

25 13 15 1 14 0 5 21 ? Explain your solution.
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Teacher: You got a 0. Miles Morales: Is that...failed? Teacher: Listen. If you answer all questions on a multiple choice test randomly, you would get a 25%. This means the only way for you to ...
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Catching a robber on one line

At x = 0, a thief robbed a bank. The thief ran one of two known directions at a constant speed, towards x < 0 or towards x > 0. The cop arrives at the crime scene some unknown time after the ...
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All the Signs point to the Second Prime…Figure out the Missing Digits

$Given$ The six Interrelated Equations A, B, C, D, E, F All equal to 3. Allowed Digits.. 1 to 9. All the missing 9 are distinct...9?s...9 Different Digits Fillin all the digits that satisfy all ...
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Prime Sequence…a little bit Unusual about the Missing Members

What are the Missing Members in this Prime Series? what is the Significance of this Sequence? $19$, $17$, $13$, $?$, $?$, $3$, $2$
108 views

Pan Digital Lucky Seven wants you to figure out all the digits

$Given$: A, B, C, D, P, Q, R, S, T are distinct digits varying from 1 to 9. AB, CD, PQ, RST are all concatenated Numbers. From the given expression , figure out all the digits to make lucky seven. ...
112 views

All Raised to the Power of U

$Given$: C, I, L, U, V are all distinct digits and can vary from 0 to 9. $LIV$, $UVC$ are concatenated Numbers. $U^U$ + $V^U$ + $C^U$ = $UVC$ $L^U$ + $I^U$ + $V^U$ = $LIV$ Solve for all the ...
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Create Numbers 1 - 100 using 1,9,6,8

Create all numbers 1 - 100 using equations made up of 1,9,6,8. Rules: Use all four digits exactly once Allowed operations: +, -, x, ÷, ! (factorial), exponentiation, square root. Parentheses and ...
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Please read part 1 or this might be confusing Since part 1, you have replaced the stolen stickers and your daughter has forgiven you. The highway ended up being a full 700km long, so you are happy ...
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Upside down A (for all) [migrated]

I am working on a voltmeter and the tolerance for it is 0.25% upside down A (for all) 1 digit. I am not sure what exactly what this means. I am guessing if my value was 19.95 'for all' could mean I ...
653 views

I am caught when I was about to steal some candies

I am a eight years old boy, I love candies, but my mom does not want me to eat any more candies because I start to have black teeth :( but I still love candies so... Today when I was about to steal ...
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There is a highway that starts in the city of Savage. You must must place distance marker signs on this highway for the outgoing traffic. According to highway code, there must be a distance marker ...
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Use 1 9 6 2 in this order to make 75

I'm looking for a solution to make number $75$ with numbers $1$ $9$ $6$ $2$ in that order and the same rules as in Use 2 0 1 and 8 to make 67. Here a copy of those rules: You must use all 4 digits. ...
189 views

Find the Missing Members of this Powered Sequence

There are 4 missing members in this small series...labeled ???. Hint 1; Hint 2: Complete the series. $191$, $426$, $931$, $???$, $???$, $646$, $971$, $???$, $???$
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Shortest time to meet

Three runners are located at the corners of an equilateral triangle, 100 meter a side. They run to a point inside the triangle and their goal is to do it as fast as possible. If they run at the same ...
477 views

Products of three primes that bound RSA numbers [closed]

Let $N$ be some number. Let $R$ and $S$ be semiprimes (ie, each is a product of two prime numbers) such that $R \le N \le S$. For quite a few numbers $N$ we can find $R, S$ such that $S-R$ is small;...
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sum and gcd june19 challenge! [duplicate]

Can anyone please help me out with the https://www.codechef.com/JUNE19B/problems/SUMAGCD question? "Example case 1: For example, the sequence A can be divided into subsequences B=(4,4,6) and C=(7)." ...
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Let M and N be single-digit integers. If the product 2M5 x 13N is divisible by 36, how many ordered pairs (M,N) are possible? [closed]

Let M and N be single-digit integers. If the product 2M5 x 13N is divisible by 36, how many ordered pairs (M,N) are possible? -- source I tried it by reducing 36 into its positive factors (1,2,3,...
513 views

2019 gold coins to share

You and your friend has found in total 2019 gold coins in a treasure hunt. Since your friend found the place to dig up, he deserves a bit more gold than you so you offer a game to share the coins to ...
148 views

Please figure out this Pan digital Prince

Given: P, R, I, N, C, E, T, O, M are all distinct digits varying from 1 to 9. PCRON, PRINCETOM are two concatenated numbers. PCRON is the highest possible number you can have fulfilling the ...
3k views

Finding maximum possible sum of GCD's of an array of n-elements

A sequence of positive integers A1,A2,…,AN. Split this sequence into two non-empty (not necessarily contiguous) subsequences B and C such that GCD(B)+GCD(C) is maximum possible.Find this maximum value....
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Make 2019 Factorial Multiplication a perfect square

N is not a square number and consists of 2019 factorial multiplication as shown below: $N=1!\times 2!\times 3!\cdots 2018!\times2019!$ At least how many factorial needed to be removed from the ...
2k views

Finding Round Integer

An integer is round if it is greater than $0$ and the sum of its digits in decimal representation is a multiple of $10$. Find an optimal procedure to compute the $N-th$ smallest round integer. E.g. ...
1k views

Finding numbers having exactly two distinct digits

We have $10^K$ road signs (numbered 0 through $10^K−1$). For each valid $i$, the sign with number $i$ has the integer $i$ written on one side and $10^K−i−1$ written on the other side. We need to ...
122 views

Don’t let this daunting equation dissuade you to deduce the desired result

Given: A, B, P are distinct digits. AA, AAA, ABB are concatenated numbers. Relations: $$P=A+A+B$$ $$(AA + ABB)^P-(ABB)^P=(AAA - A) ^P+(B+B^B*B)^P+(B^B)^P$$ Don’t be afraid to make reasonable ...
211 views

Mathematical Sequence Based on Prime Numbers

This sequence is based on prime numbers Hint 1: 16, 17, 11, 16, 10, 8, 13, 7, 14, 8, 11, 7, 5, 10, 4, 11, 5, 10, ?, ?, ? What are the final three numbers?
For how many integers $N$ is the rational function $\frac{N^2-2N-15}{N^2-N-12}$ also an integer?