I've been looking at many formula's both in mathematics and physics, this applies right across the board and I'm just wondering why soooo many of them have something or other squared. Why always squared and not cubed or something else? What is the nature for squaring something all the time?

Take for example

$\displaystyle t' = t {\sqrt{1-\frac{v^2}{c^2}}}$

I just seem to notice that in every single math topic I start learning there is always some key formula or something that involves squares. Hardly ever do I see cubes or greater. Just wondering why...