Math teachers were ambivalent about them, because at that time most of them did only basic arithmetic and they were more interested in us learning how to keep and maintain those skills on our own. Higher math functions came later, and by that time I had discovered that the alphas and numerics had conspired together to keep me out of the club that understood their interactions.
Nowadays, a calculator is most probably an app on your computer or on your phone, and you can likely find one that will mimic the appearance of those first handhelds. And thus a new generation learns how you can tell someone to go to "7734 upside down" without getting in trouble from clueless adults who had no idea what we meant, snicker snicker.
Before printed circuits and such, calculating machines had to use gears, somewhat like a clock would in advancing its hands properly according to the passing of seconds, minutes and hours. At io9, they've assembled some pictures of early calculating machines, and the earliest ones are as much a work of art as they are functional, in the same way a fine old watch might be:
|Johann Helfrich Müller's adding machine, 1784|
On the other hand, if you get ticked at one of these when your checkbook balancing leaves you three cents off no matter how many times you do the addition and you smack it with your hand, that's probably going to draw some blood.