I have an old scientific Casio calculator. I think I got it for my A levels or it might have been several years after. That would make it between 30 and 40 years old. It still works except I don't trust its power supply. I have a torch that takes three D type batteries. It was a bright torch for its day. I have a Seiko watch my father gave me for a 21st birthday present, so that is over 30 years old. It has only needed one battery change.