don't know the formula for the circumference of a circle. don't know the formula for the area of a circle. Get 27/6 to be 1.5 think that 3 squared is 6, and that 6 squared is 12. think that the square root of 36 is 18. have no idea what the quadratic formula is. wonder why they struggle with AS-Level maths when they got an A at GCSE. Beats me. Why do they struggle at AS-Level? Any ideas?