^^^^
On an every day operational basis, the only quick mental math I have to do is the Glideslope ROD. And thats about it.
Oh and ToD depending on which plane I use. Unpressurised. 500ft per minute is not a hard one.
Altitude x3 or x2 for pressurised aircraft.
GPS are now installed in pretty much every aircraft. And if not, DME is also there.