Complex Numbers
These numbers are complex, they are hard to understand, just like your ex. Except they don’t sleep with your best friend and give you chlamidia.
A complex number is a number that can be written in the form $a + bi$ where $a$ is the real part and $b$ is the imaginary part. $i$ is called an imaginary number because it is defined so that $i^2=-1$. When you plot the real part of complex numbers in the $x$ axis and the imaginary part in the $y$ axis, you get a pretty nice way to represent numbers as well as rotations.