I used to be pretty good at Maths when I was still in certain grades, but things have changed anyway. Back to the main topic, I have an exam coming up very soon, like in 4 days, and I don't even know basic things. Main topics I need to learn are differential equations and calculus, a lot of it, like integrals and stuff. I am a pretty fast learner when I invested into it, so any tips to study effectively without medication of any kind? Anything helpful, any fun way to learn, maybe. the problem is I get hardtime learning the foundation after a decent foundation. Then I can actually learn at a very rapid speed nd be good at it.

Anything would be helpful. Thanks in advance