Why $ e^{-2\pi} \neq 1? $
140459
Why is $\left(e^{2\pi i}\right)^i \neq e^{-2 \pi}$?
95145
Does $\exp(2ir\pi)$ equal $1$? What's wrong?
41191
How to prove this $\pi$ formula?
11059
Verify the identity: $\tan^{-1} x +\tan^{-1} (1/x) = \pi /2$
27347
Verify that $\left|\int_{\gamma} \exp(iz^2)dz\right| \leq \frac{\pi\big(1-\exp(-r^2)\big)}{4r}$ where $\gamma(t)=re^{it}$, for $0\leq t \leq \pi/4$.
130686
How is $3\pi-10$ element of $[-\pi/2,\pi/2]$?
47845
Mirror algorithm for computing $\pi$ and $e$ - does it hint on some connection between them?
34430
Why does $(\frac{p-1}{2}!)^2 = (-1)^{\frac{p+1}{2}}$ mod $p$?
2786
The staircase paradox, or why $\pi\ne4$
88989
Why $x<\tan{x}$ while $0<x<\frac{\pi}{2}$?
95266
Show $|t|\leq \pi \Rightarrow |e^{it}-1|\geq 2|t|/ \pi$
48086
Why is this series of square root of twos equal $\pi$?
59818
Why $(-2)^{2.5}$ isn't equal to $((-2)^{25})^{1/10}$?
106803
How to see $\cos x \leq \exp(-x^2/2)$ on $x \in [0,\pi/2]$?
82391
Why does $\sum_{k=1}^{\infty}\frac{{\sin(k)}}{k}={\frac{\pi-1}{2}}$?
43834
Simple Complex Number Problem: $1 = -1$
65300
Why is $\pi$ irrational?