Yes, a calculus formula might have been used somewhere in that process, and was used by the finance person and dev. That doesn't mean I, or any other person, needed to know it.
As a dev at a financial institution, I've never needed to implement calculus formulas. Most calculations and formulas I've dealt with are algebra and stats. These usually are just a matter of using standard libraries too. So most devs aren't implementing formulas themselves, but just utilizing standard libraries.