For over a decade I've been using emulators of the calculators I grew up using on all my android phones. I see no point in changing my "weird" ways.

I use RealCalc for most things (RPN style). Has many functions like a scientific, but I mostly stick to the basic four and it also converts units.

I switch to Graph89 when I need a graph/table involving trig or polynomial approximations. Sometimes I'll even write a basic program. If I'm using this app I probably also have measuring tools out for a DIY project.

I go to spreadsheets for anything beyond that using "Office: Planmaker". It handles the xlsx format perfectly! That's how I do my monthly budget, health tracking, etc. For reasons beyond my understanding, some people are still impressed seeing proper full-featured spreadsheets done quickly on a phone.