I use a TI-89 I’ve used since high school 20 years ago a couple times a week. Mostly to simplify equations or rewrite multi-variable equations to solve for a pa

I use a TI-89 I’ve used since high school 20 years ago a couple times a week. Mostly to simplify equations or rewrite multi-variable equations to solve for a particular variable. I could do it by hand but why bother and why introduce human error. I’ve never found a tool that made that sort of symbolic math simpler. I have TI-92 but I find the larger form factor cumbersome and without benefit. I use a TI-89 emulator on my phone as well… I just know my way around it and how to do everything I need to.