This depends on what sort of science you want to continue on to do. In general, a firm background in maths always helps any scientist! In addition, I use computer programming a lot, so a coding background is often very useful as well. Depending on which area of science you want to continue to, physics, chemistry or biology will be essential! Although a lot of topics contain quite a bit of overlap! For example, I had to learn some chemistry to be able to understand some processes that happen in space!
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