Is one allowed to wear a calculator wrist watch on shabbos? Is there a problem of muktzah or of inadvertently pushing the buttons?
It is permitted to wear the watch on Shabbos.
The primary purpose of the watch is to tell the time, and therefore there is no issue of mukzeh on account of the calculator.
The concern for pressing buttons is likewise not a problem, because there is no intention to press buttons, and in addition it is likewise not a certainty that buttons will be pressed. Even if a button is inadvertently pressed, it is therefore a davar she-eino miskaven, which is permitted on Shabbos.