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Shuri2060
  • Member for 7 years, 2 months
  • Last seen this week
  • UK
1070 votes
32 answers
149k views

How long will it take Marie to saw another board into 3 pieces?

  • 10.1k
96 votes
4 answers
33k views

Finite subgroups of the multiplicative group of a field are cyclic

  • 969
37 votes
4 answers
13k views

Cross product in higher dimensions

  • 65.4k
28 votes
2 answers
928 views

Matching red to blue dots

  • 619
15 votes
2 answers
1k views

Can every number $n$ be written as the sum of $n$ different prime numbers?

14 votes
3 answers
2k views

If you have two envelopes, and ...

  • 1,897
13 votes
1 answer
285 views

$2^n$ base $5$ contains more than ones and zeros?

  • 335
12 votes
1 answer
958 views

Prove that a quadrilateral, and the quadrilateral formed by the orthocenters of four related triangles, have the same area.

10 votes
1 answer
553 views

Find all primes for which $p^p - 2$ is a perfect square

10 votes
0 answers
382 views

Write Occam's razor rigorously

9 votes
4 answers
350 views

Is there a closed form formula for the recursive sequence: $x_n = x_{n-1} + \alpha\sqrt{x_{n-1}}$

8 votes
1 answer
221 views

Prove that the number $2a+b+c$ is not a prime number [closed]

8 votes
1 answer
918 views

Sum of $n$ numbers divisible by $n$

8 votes
0 answers
1k views

Movement time of object with constant jerk, limited acceleration and velocity

  • 181
8 votes
4 answers
258 views

Sum: $\sum\limits_{n=0}^\infty \frac{n!}{(2n)!}$

7 votes
3 answers
327 views

Not a run of the mill 20 balls in a bag problem!

  • 71
7 votes
1 answer
503 views

If $f(x+y) = f(x) + f(y)$, $f(1) = 1$ and for all $x,y$, $f(xy) = f(x)f(y)$ or $f(xy) = f(y)f(x)$, then $f$ is a homomorphism or an anti-homomorphism

  • 3,869
6 votes
1 answer
352 views

Find the number of permutations of $1,2,3...,n$ such that $a_{i+1}\neq a_i+1$ for $ i<n $ if $a_i$ is the i-th element in the permutation?

  • 676
6 votes
1 answer
1k views

What is the chance the product of four dice would equal 144?

5 votes
3 answers
5k views

How do I find the area of a general closed curve? (And then generalisation to multiple dimensions)

  • 4,129
5 votes
0 answers
49 views

Two polynomials sharing two values [duplicate]

5 votes
1 answer
76 views

Why does this differentation output correct result? [duplicate]

5 votes
2 answers
162 views

First to 1000 rolls wins

  • 148
5 votes
0 answers
85 views

Is $\int^0_0 x^{-1} dx$ defined? [duplicate]

  • 4,129
5 votes
2 answers
2k views

Riemann hypothesis, random walks and Möbius function

  • 1,561
5 votes
3 answers
428 views

Number of pairs of nontrivial relatively prime divisors

4 votes
1 answer
3k views

A nice way to do Euler's method on a calculator?

  • 4,129
4 votes
0 answers
80 views

$x_n=\sin(x_{n-1}),x_{0}\in (0,\pi)$, find limit $x_{n}\sqrt{n}$ [duplicate]

  • 593
4 votes
1 answer
1k views

Odds of guessing a sequence of cards in order

4 votes
0 answers
89 views

Computation of Matrix inversion