PURPOSE: To operate and display input from the outside by making combination use of a part of watch elements of the digital type electronic watch.

CONSTITUTION: In order for the watch to operate as an electronic watch, its crystal vibrator 2 is operated to count the hour, minute and second. A calculator is constituted by a keyboard switch 17, an arithmetic and control unit 18, a register 19 and display devices 10 thru 16. The display devices 10 thru 16 are commonly used for the watch display part and the calculator may be constituted only by the elements encircled in the frame 20, thus not only the reduction in cost but also the reduction in thickness may be achieved and the merchandise value enhanced.