I have had an HP 12c since 1988. All I have ever done is replace the batteries. A quality product.
Same experience here. Both 12C and 15C running strong. Amazing machines.
A physicist(15c), an engineer(15c) and an economist(12c) are stranded in the desert. They are hungry.
Suddenly, they find a can of corn. They want to open it, but how?
The physicist says: “Let’s start a fire and place the can inside the flames. It will explode and then we will all be able to eat”.
“Are you crazy?” says the engineer. “All the corn will burn and scatter, and we’ll have nothing. We should use a metal wire, attach it to a base, push it and crack the can open.”
“Both of you are wrong!” states the economist.“The solution is simple: ASSUME we have a can opener.”
HP 12c for the win!