Reputation
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95/100 score
43/20 answers
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1d
accepted Number of divisors $d$ of $n^2$ so that $d\nmid n$ and $d>n$
2d
accepted If $|H|=112$ then $A_7\cap H \lhd H$?
Aug
27
accepted Sum of three cross products is zero.
Aug
26
accepted a matrix of rank $r$ satisfies a polynomial of degree $r+1$.
Aug
20
accepted Tzaloa 2015 game problem (piles with $1,2,4 \dots 2^{19}$ coins each)
Aug
19
accepted Slick proof that if an open set contains $\mathbb Q$ it has all irrational numbers, except a countable amount.
Aug
13
accepted What is the maximum area two non intersecting circles can cover if they are contained in a unit square?
Aug
13
accepted Can three diagonals in a $2k+1$-gon intersect?
Aug
12
accepted Proof a Rng cannot have exactly five non-zero divisors.
Aug
11
accepted How many words can be made with $7$ A's, $6$ B's, $5$ C's and $4$ D's with no consecutive equal letters.
Jul
19
accepted Subgroups of $S_n$ with exactly one fixed point for each element all have the same fixed point.
Jul
16
accepted A positive integer is equal to the sum of digits of a multiple of itself.
Jul
16
accepted What is the intuition behind generating functions? What makes them valuable?
Jul
8
accepted Continuous bijective function between the same topology that is not a homeomorphism.
Jul
8
accepted Explanation of a joke on abelian groups (grapes).
Jul
7
accepted IMC 2008 first problem first day. Finding continuous functions so $x-y\in \mathbb Q \implies f(x)-f(y)\in \mathbb Q$
Jul
6
accepted 2014 IMC first problem first day (eigenvalues of a product of symmetric matrices).
May
31
accepted Finding all solutions to $x^2+y^2=2010$
May
29
accepted Integers of the form $x^2+2y^2$.
May
29
accepted Topology problem I invented (characterizing spaces in which every open set is closed)