Using the curriculum at Berkeley as an example, biomedical engineering requires a minimum of four courses or approximately 16 units. The first two are introductions to differential and integral calculus. The third class covers parametric equations, vectors, 3 dimensional euclidean spaces, etc. The last of the four minimum requirement courses covers basic lineaer algebra, matrix arithmetic, fourier series and so on. Now bear in mind that engineering itself is heavily dependent on math, so this is no exception, and this series will be applicable in whatever engineering branch you decide on. But also keep in mind that this series is the bare minimum needed for your undergraduate work. And the better news is that if you really are jazzed up on engineering in general, you'll enjoy these classes as well. And more, in engineering, you'll be learning stuff you'll be putting to actual use. I personally must have switched majors three times with no problem using my previous coursework at all.