**Perfect Woman**

By the way, the formula is called Euler's formula.

A very famous formula that students encounter during their first year (or even last year of high school if they are lucky). It is a simple formula, not even difficult to prove or mentally visualize, but it involves (and mix in a very delightful way) various fundamental notions (arithmetics, algebra, analysis and geometry) which, a priori, have nothing to do with one another.