So I've been reviewing over the courses for a Physics degree at a University I plan to attend. The required math is Calculus I, II, III and Ordinary Differential Equations. I've been told and read in quite a few different places that I should take more math classes, like Partial Differential Equations and Numerical Analysis. Now, I've seen that the University offers a lot of these good math classes that will help me delve deeper, the only problem is that I'm afraid of going over this "Credit Limit" thing. Basically If I take more than 136 credit hours or something I'll be charged an extra fee. Personally, I think it's kind of dumb, if I'm paying tuition to and fees to take the classes anyway, but whatever, that's not the point. If I do a minor in mathematics, I'll be taking the four mentioned classes along with Linear Algebra and two other math classes. And since it's a minor, I won't have to deal with the credit limit thing. I feel like that won't be enough to dive into what I really want to dive into, though. If I did the math minor I'd be thinking of taking Partial Differential Equations and maybe Probability and Statistics. Whereas if I do a dual major in math, I'll be able to cover all those other math classes that would really help, but it would be a very large workload added onto an already large one with the Physics degree itself. Not to mention I'd really like to take some Computer Science classes beyond what's required for the degree and maybe get a minor in that. So if I were to do the math minor, what would be the best two other math classes to take that would help me on my Physics journey? Should I try for the dual major or not? And if I simply do the minor, how else can I study these mathematics outside of college to get a good grasp on them? On a side note, the specific area of Physics I'm interested in is Astrophysics and Planetary Science. If that helps narrow down what math classes I should take.