[ptaipale]

My son (in high school) took into use a HP-15c that my wife bought in 1987. Alas, it broke after travelling back and forth between home and school for a few months. A true loss, but it wasn't as strong as I thought it would be.

In 1985, I was preparing for the matriculation exam (at end of high school). I was worried that my Sharp EL-506 battery would run out in the middle of this important exam, because it was already 3 years old. However, I did not change it. It lasted the matriculation exam. It lasted also my MSc studies and army, 9 years altogether. And beginning of my working career. And it actually still works, though nowadays I don't need it so it's just at the bottom of the drawer. But it is OK, 31 years after buying it, with original batteries and some significant use during high school and uni. I just don't understand.