How do we know which formulas we need to learn for the exam?

When learning new content, I know it is really intimidating seeing how many new formulas and equations are needed to answer questions, however I also know how easy it is to get on top of it all! My main piece of advice would be to print off the formula booklet used by your exam board and become familiar with it. Most formulas needed to answer the exam questions will be included in this booklet, however there are certain ones which are not. On the other hand, after the 2 years you will spend learning the course, you will find that you already know most of the formulas needed and will not have to use the formula book in the exam! After doing so many practice papers, you will get used to doing the questions to the point where it will become natural, so you will be ready for the exam without even realising it.