Joffan

Interested in mathematical counting puzzles and many others ${\overset\infty \smile}$

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$x(p − x)y(p − y)$ is square implies $x = y$

number-theory elementary-number-theory asked Oct 24, 2017 at 16:19

math.stackexchange.com

10 votes

Curiosity wheel damage

rovers curiosity asked Feb 1, 2015 at 4:56

space.stackexchange.com

7 votes

Reluctant roots: $n$ is a primitive root of $p$ but not of $p^2$

number-theory primitive-roots asked Apr 16, 2018 at 0:55

math.stackexchange.com

7 votes

Jessica the Combinatorics Student, part 2

combinatorics pigeonhole-principle asked Jul 8, 2016 at 23:09

math.stackexchange.com

7 votes

When does $2^{2m}+2^m+1$ divide $10^{2m}+10^m+1$?

number-theory elementary-number-theory asked Sep 22, 2017 at 16:13

math.stackexchange.com

6 votes

$a^{13} \equiv a \bmod N$ - proof of maximum $N$

algebra-precalculus elementary-number-theory prime-numbers modular-arithmetic asked May 14, 2015 at 16:22

math.stackexchange.com

5 votes

Size of a $3$-colored square grid to produce a monochrome rectangle

combinatorics coloring asked Sep 4, 2017 at 17:44

math.stackexchange.com

Top Answers

Prove that the equation $x^2-y^2 = 2002$ has no integer solution

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How many subsets of set $\{1,2,\ldots,10\}$ contain at least one odd integer?

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Where does the constant increase by 2 of differences between integer square values come from?

math.stackexchange.com

Every point of a grid is colored in blue, red or green. How to prove there is a monochromatic rectangle?

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Is there a combinatorial interpretation of the triangular numbers?

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How many pairs of numbers are there so they are the inverse of each other and they have the same decimal part?

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The sum of the squares is less than or equal to the square of the sums for all n.

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Is there an English idiom for trying to do two things at the same time and failing at both of them due to splitting your effort?

english.stackexchange.com

How do I find the diameters of the circles in this geometry puzzle?

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What is the sum of the $81$ products in the $9 \times 9$ multiplication grid?

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Proving that modular inverse only exists when $\gcd(n,x)=1$

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How to build a trap to last the ages?

worldbuilding.stackexchange.com

Prove that the expression is a perfect square

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Which of the following numbers is greater?

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Elegant Proof of a simple inequality

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Find two numbers whose sum is 20 and LCM is 24

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A rhopalic sentence of at-least 5 words, beginning with as long word as possible

puzzling.stackexchange.com

If $a^2 + p^2 = b^2$ then $2(a+p+1)$ is a perfect square

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minimum number of steps for knight in chess

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Is there way to know if ODD number can be expressed as sum of two primes?

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Finding consecutive naturals that all fail to have inverses modulo $70$

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Longest word with adjacent letters on a keyboard

puzzling.stackexchange.com

Draw the EU Estimated Sign

codegolf.stackexchange.com

Multiple-choice: sum of primes below $1000$

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How does atan(1) * 4 equal PI?

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180 degree rotation matchstick equality

puzzling.stackexchange.com

Wife can't figure out husband's secret account password

puzzling.stackexchange.com

Ant walking on a number line

puzzling.stackexchange.com

How to compute $\sqrt{1+2015\sqrt{1 + 2018 \cdot 2016}}$

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Showing n! is greater than n to the tenth power

math.stackexchange.com