Yep, my dad wouldn't let me get my first handheld (LED display!) calculator ~50Y ago until I could prove to him that I didn't need it for simple things such as

Yep, my dad wouldn't let me get my first handheld (LED display!) calculator ~50Y ago until I could prove to him that I didn't need it for simple things such as multiplications up to 12... (Yes, 12, since we still had/have feet and inches for example...)