i guess u r taking N level this yr rite?
well, I can say maths need practise.
It wont help if u jus memorise the formula blindly without knowing the concept. I used to fail maths when I'm in pri school. But after what I was told by one of my pri teacher that maths need practice and knowing the concept well will let u pass without worries. After that,I managed to get As throughout till now.

U can starting doin ur ten yr series from first page till the last and from the last till the first. Keep on practising till the day u enter the exam hall....