want to understand Calculus to become scientifically literate.

I really think a lot is less about understanding "Calculus" and more about understanding the specific use of symbols and formula within the context.

So you probably want to look at the equations specific to the type of science that you're interested in, and work backwards to find out what you're missing.

I could be wrong though... Actually I remember a scientific calculator being pretty much required for calculus, but I'm sure a computer can do that... It's been almost 20 years since I did any calculus.