I found a basic understanding of maths is all that is really required. The ability to transpose equations effectively and quickly is a definate must though. (V=I x R and derivations there of etc)
If you are not long out of school, or did a science/engineering based subject at college/uni it wont be much of a problem for you. If you are an old grunter like me, it might be worth trying to find a local maths teacher who is willing to do a bit of one to one for revising O Grade/ O Level / GCSE(?) maths. You shouldn't need much to get back into the swing of things.