I saw this at Business Insider – 22 Products That Really Do Last A Lifetime
“My trusty TI-30-X got me through all of grades six to 12, and I’m still using it in college on the same battery.”
I have a TI 21a Solar Calculator that must be a good ten years older than the model shown above. I use it almost every day and just like the guy above have not had to change the battery even once. TI should be building electric cars.