Economics prerequisites

Question: What are the (math) concepts I need to know before starting any economics course?

Hi, I want to do the Economics courses (Micro-, Macro- and Finance) In the first lesson they talk a lot about "the math behind economics" so I started to worry my math is not advanced enough to fully enjoy this course...
I do not want to interrupt my econ course to go back to math classes. At the moment, my math level on Kahn is that I completed 1-8th grade courses.