The maths behind the Mandelbrot fractal is based on complex (sometimes called imaginary) numbers.
Whilst they are a very abstract concept, they form the foundations for a lot of advanced maths. You can cope without them, but calculations become a lor more difficult.
On the right hand side of this page you will find three lessons covering the basics of complex number. The first explains what they are, the second shows how they can be used to solve a problem and the third shows how they make up the Mandelbrot plot.
If you wish to learn more about how the Mandelbrot fractal is made or about Lewis Fry Richardson then please use the following links.