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WimC
  • Member for 10 years, 5 months
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131 votes
Accepted

Why is $\frac{987654321}{123456789} = 8.0000000729?!$

77 votes
Accepted

Is there a simple, constructive, 1-1 mapping between the reals and the irrationals?

60 votes

Prove that $\log(n) = O(\sqrt{n})$

59 votes

Can every proof by contradiction also be shown without contradiction?

35 votes

If $n\ne 4$ is composite, then $n$ divides $(n-1)!$.

35 votes

Making 400k random choices from 400k samples seems to always end up with 63% distinct choices, why?

33 votes

How many positive integers $< 1{,}000{,}000$ contain the digit $2$?

28 votes
Accepted

Please prove that the Probability Mass Function (in Binomial Distribution) is less than 1.

27 votes

Why does $ \int_0^1 \lceil { x\sin({1 \over x})} \rceil \,dx = 1 - \frac{\log(4)}{2\pi} $?

23 votes
Accepted

Proving that $\sin x \ge \frac{x}{x+1}$

21 votes

Mapping half-plane to unit disk?

21 votes
Accepted

How to efficiently generate five numbers that add to one?

20 votes

Integral $\int_{0}^{1}\ln x \, dx$

18 votes
Accepted

Proof that a function with a countable set of discontinuities is Riemann integrable without the notion of measure

18 votes

Calculate sum of $\sum_{n=1}^{\infty}(-1)^n\frac{\ln n}{n}$

17 votes
Accepted

Limit of complex function

17 votes
Accepted

Find $\sum_{n=1}^\infty {\frac {f(n)} {n(n+1)}}$ where $f(n)$ is the number of $1$s in $n$'s binary expansion

16 votes
Accepted

What's the most elementary way to solve this trigonometric problem?

16 votes
Accepted

101 positive integers placed on a circle

15 votes

Proving that $\lim_{z \to 0} \frac{\bar{z}}{z}$ does not exist

15 votes
Accepted

Disproving an "almost true" trigonometric identity

15 votes
Accepted

How do we check if a polynomial is a perfect square?

14 votes

Explaining a Fibonacci

14 votes

A bound on a sum of five sines

13 votes

Without using approximation, prove that $ \ln(4)<\sqrt{2}$.

12 votes
Accepted

How can I evaluate this improper integral?

12 votes

Are there any simple ways to see that $e^z-z=0$ has infinitely many solutions?

12 votes
Accepted

Do there exist equations that cannot be solved in $\mathbb{C}$, but can be solved in $\mathbb{H}$?

12 votes

Prove that $p \in \mathbb{R}[x]$ can be represented as a sum of squares of polynomials from $\mathbb{R}[x]$

10 votes

Proof of a simple property of real, constant functions.

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