Right, I am a 737-300/400 and 800 pilot, get paid well and enjoy it, got a B at O Level Maths many many many years ago. also got a B at Science, fat lot of good both of those did me. Can you use a Calculator???? Can you lean some Formula's???? Can you retain information???? Well done you can do it.
My CV does not mention my O Levels, or A Levels. It does not need to. I have friends who all have got flying jobs with jets in the UK in the last few years with NO qualification all!!!!! I have even had a Line Training Captain who never sat an exam in his school life.
My point is this, yes, you should be okay with basic maths, add, subtract, divide, multiply. further than that use the plastic brain (Calculator, to those who have not been to Bristol Groundschool). The CRP-5 is not hard to master. You need to understand English, for deciphering the ATPL's. But don't go back to school for them.
Hard work and you will get there