Hello Mark Cappiello!

Math in College could be done in varieties of ways, which depends on the course you take, compared to Highschool i.e. Engineering, Medicine, etc. However, as for pure Mathematics and not Applied Math, in College it is often found more theoretical, analysis, abstract and complex compared to the Highschool Math.

Furthermore, Highschool Math only involves problem solving and calculations which may be less found in University level due to the University level involves proofs and abstractions. 

Hence, I'd recommend you learn the basics of logic and theory in pure Mathematics which could be valuable. A course sequence for College Math could be Calculus, Trigonometry, Algebra and Functions. 

Since Math has loads of varieties during University level, I'll assume you would like to go for the pure Mathematics. I'd recommend 'A guide to studying Mathematics at Oxford University - How do Undergraduates do Mathematics', and the 'A first course to abstract Mathematics - Ethan D. Bloch's Proofs and Fundamentals' for a start. 

- Hope you find this helpful!

~Galaxy

I appreciate the effort put into your response, however,  I am talking specifically about Khan Academy courses. In what order should Khan Academy math courses be taken.  Maybe if they could be numbered that would be helpful. 

Mark Cappiello
Calc AP AB/Derivative Calculus/Calc I
Calc AP BC/Integral Calculus/Calc II
Linear Algebra
Multivariable Calculus
Differential Equations