It's like solving Math issues. You should understand, that professor will not always be near you, helping you solving those expressions. What if using basic calculator solving huge algebra functions isn't so good idea? When I was reading this article with reviews on calculators (
https://bestcalculators.net/best-printing-calculator-reviews/), I've realized how silly I was trying to solve my functions with my Android in-built calculator. After I got Casio - it became much easier.