“Every complex number has a complex conjugated twin, which is inverted—a mirror image—along the x-axis and has the same real part. Only the imaginary part is different: the equal-size opposite. If you multiply a complex number by itself, you get another complex number. But if you multiply a complex number by its complex conjugate, you get a real number.
So it’s important to find your complex conjugated twin. And to multiply yourself by him—then the product will be real.”