Calculator in iOS can’t divide 729 by 27 (twitter.com)

729 divided by 27 equals 27. That is why if you tap "=" its still displaying 27 and if you tap it again it divides by 27 and a 1 is displayed. So the Calculator is working fine.

So the answer you get is the same as you've typed in (27). Hardly "can't divide" ...

This is a case where a bit of skeuomorphism (gasp) might have been useful. The momentary screen refresh flash on old-style LCD calculators helped indicate to the user that the input had been acknowledged. In the iOS calculator, the subtle darkening of the "=" button (which is also almost entirely concealed by the rest of the curled thumb in right-handed users) is just not enough feedback on its own.

I like Google's UI better. It's more obvious

http://gfycat.com/SelfishNegativeDouglasfirbarkbeetle