Revising maths is really important. I tend to always get A*s, but on my end of year I started freaking out and got distracted.
AN EXAM INVIGILATOR FELL OVER BEHIND ME AND THEN STOOD THERE FOR THE WHOLE EXAM I COULDN'T CONCENTRATE
I got a B, even sinking to the point where I wrote "7+12=17" on my paper. Trust me, revise for maths.