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553 Answers

Newest Activity Votes
114
Why is $\frac{987654321}{123456789} = 8.0000000729?!$
May 19 '13 at 8:35
57
Can every proof by contradiction also be shown without contradiction?
Nov 24 '12 at 16:06
54
Is there a simple, constructive, 1-1 mapping between the reals and the irrationals?
Oct 2 '13 at 18:18
50
Prove that $\log(n) = O(\sqrt{n})$
May 16 '12 at 16:36
34
Making 400k random choices from 400k samples seems to always end up with 63% distinct choices, why?
Jul 21 '14 at 16:14
33
How many positive integers $< 1{,}000{,}000$ contain the digit $2$?
Feb 9 '14 at 17:53
26
Why does $ \int_0^1 \lceil { x\sin({1 \over x})} \rceil \,dx = 1 - \frac{\log(4)}{2\pi} $?
Jul 29 '15 at 12:26
26
If $n\ne 4$ is composite, then $n$ divides $(n-1)!$.
Jun 30 '12 at 10:13
23
Proving that $\sin x \ge \frac{x}{x+1}$
Nov 6 '12 at 20:30
21
How to efficiently generate five numbers that add to one?
Jun 16 '13 at 17:30
20
Please prove that the Probability Mass Function (in Binomial Distribution) is less than 1.
Dec 8 '12 at 6:38
18
Calculate sum of $\sum_{n=1}^{\infty}(-1)^n\frac{\ln n}{n}$
Jan 10 '13 at 22:07
17
Limit of complex function
Nov 24 '12 at 11:19
16
integral of $\ln x$ from 0 to 1
Dec 25 '12 at 9:53
15
Disproving an “almost true” trigonometric identity
Aug 26 '14 at 5:13
15
Find sum of the series
Mar 16 '14 at 9:48
15
Proving that $\lim_{z \to 0} \frac{\bar{z}}{z}$ does not exist
Nov 4 '12 at 18:13
15
Mapping half-plane to unit disk?
Feb 29 '12 at 8:55
14
A bound on a sum of five sines
Apr 29 '13 at 7:34
12
101 positive integers placed on a circle
Jan 20 '13 at 10:54
12
How can I evaluate this improper integral?
Jan 1 '13 at 18:22
12
Explaining a Fibonacci
Oct 28 '12 at 19:45
11
How do we check if a polynomial is a perfect square?
Sep 5 '14 at 18:50
11
Show that $e^x \geq (3/2) x^2$ for all non-negative $x$
Jun 23 '13 at 13:51
11
Proof that a function with a countable set of discontinuities is Riemann integrable without the notion of measure
Dec 23 '12 at 21:27
11
Are there any simple ways to see that $e^z-z=0$ has infinitely many solutions?
Apr 28 '12 at 10:14
10
A field having an automorphism of order 2
Jul 17 '14 at 6:19
10
Limit of $\left(1-\frac{1}{n^2}\right)^n$
Nov 24 '13 at 16:46
10
Proof of a simple property of real, constant functions.
Feb 26 '12 at 18:56
10
Fibonacci's final digits cycle every 60 numbers
Feb 26 '12 at 10:03
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