Calculus, as well as other mathematics in general is not just about "plug + chug" type problems. Mathemeticians look at things, question how they work, and after understanding how they work derive a formula that governs how the thing in question works, making it easier for future mathematicians to deal with the aforementioned object and eliminating work they'd have to do to figure it out themselves, allowing them to work on new problems... if everyone had to figure out the special relationships in 30-60-90 triangles or that the volume of a sphere is four thirds pi r cubed for themselves, math wouldn't be nearly as far as it is today.

The same applies with music theory. People questioned why the notes C, then D, E, F, G, A, B sounded good. They saw that D, E, F#, G, A, B, C# also sounded good. Then someone noticed the pattern and derived a mathematical formula to attain the major scale. Whole, whole, half, whole, whole, whole, half. Music theory is pretty much the math governing music. If no one had told you the "formula" to make major and minor chords, it'd be hell to come up with chord progression to jam with your buddies.

Question the way things work and come up with your own formulas to create kick-ass music!