Problems

 Complex number calculator (hackmath.net)

One uses Euler's formula - which he dubbed 'our precious jewel' - to move around

the complex plane. With the pi value positive, we go counter-clockwise. With

negatives, we go clockwise...

                                                              

So it is, e^(i*pi) = -1

How does it work. The pi element represents the length of the circle arc we want to see

on the i-axis.