Life span of an HP Calculator

[Maximilian Hohmann]

My oldest one that still works is an HP-35, first version, from 1972. It has a little issue with the power switich but apart from that everything works perfectly. But since I didn't own it all those 52 years I can't know how much it was really used.
After ca. 1980 I haven't seen many first generation LED calculators being actually used so I guess that it spent 40+ years dormant in a drawer.