Why can't $\pi$ be expressed as a fraction?
37642
Why is $\pi$ irrational if it is represented as $C/D$?
49444
Why isn't $e^{2\pi xi}=1$ true for all $x$?
96584
Why isn't the volume formula for a cone $\pi r^2h$?
41191
How to prove this $\pi$ formula?
17963
I have learned that 1/0 is infinity, why isn't it minus infinity?
95637
Justifying Calculations on $f(n)=\frac{1}{2 \pi}\int_{-\pi}^{\pi}\theta e^{-in \theta} d \theta$
34762
Why isn't $\int \frac{1}{x}~dx = \frac{x^0}{0}$?
32316
Are all integers fractions?
109175
Why is it hard to prove whether $\pi+e$ is an irrational number?
48086
Why is this series of square root of twos equal $\pi$?
64941
Why is $1 - \frac{1}{1 - \frac{1}{1 - \ldots}}$ not real?
105423
Why doesn't every integral from 0 to $2\pi$ equal zero?
28441
Why can't the indefinite integral $\int\frac{\sin(x)}{x}\mathrm dx$ be found?
68155
Explanation why $\frac{(x-1)!-(x-1)}x$ is always an integer for prime $x$
82391
Why does $\sum_{k=1}^{\infty}\frac{{\sin(k)}}{k}={\frac{\pi-1}{2}}$?
30781
Why the representation in the form of $Z'X(X'X)^{-1}X'Z$ can not be simplified into $Z'Z$
155740
Newton's Law of Graviation: Why $G$ and not e.g. $\dfrac{1}{4\pi G_0}$?