Ways to write "50" A really good friend of mine is an elementary school math teacher.  He is turning 50, and we want to put a mathematical expression that equals 50 on his birthday cake but goes beyond the typical "order of operations" problems.  Some simple examples are 
$$e^{\ln{50}}$$
$$100\sin{\frac{\pi}{6}}$$
$$25\sum_{k=0}^\infty \frac{1}{2^k}$$
$$\frac{300}{\pi^2}\sum_{k\in \mathbb{N}}\frac{1}{k^2}$$
What are some other creative ways I can top his cake?  
I should note that he is an elementary school teacher.  Now he LOVES math, and I can certainly show him a lot of expressions.  I don't want them so difficult that it takes a masters degree to solve, but they should certainly be interesting enough to cause him to be wowed.  Elementary functions are good, summations are also good, integrals can be explained, so this is the type of expression I'm looking for...
EDIT:: I would make a note that we are talking about a cake here, so use your judgement from here on out.  Think of a normal rectangular cake and how big it is. Hence, long strings of numbers, complex integrals, and long summations are not going to work.  I appreciate the answers but I need more compact expressions.

We also have
\begin{align*}
50 &= 11+12+13+14 \\ 
&= (8+4)+(8-4)+(8\cdot 4)+(8/4) \\ 
&= 4^2 + 4^2 + 3^2 + 3^2\\
&= 6^2 + 3^2 + 2^2 + 1^2\\
&= (7+i)(7-i) \\
&= (10-\color{red}{5})(10-\color{red}{0})\\
&= 10(\color{red}{5}+\color{red}{0})\\
&= \sqrt{30^2+40^2}\\
&= \sqrt[3]{170^2+310^2}\\
&= \sqrt[3]{146^2+322^2}\\
&= \sqrt[3]{50^2+350^2}\\
\end{align*}
Finally $50= 2 + 4 + 8 + 12 + 24$ and $\frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \frac{1}{12} + \frac{1}{24} = 1$.
