Abstract: A digital clock includes: an acoustic-signal receiver and amplifier, a monostable circuit; a display selector consisting of a pair of flip-flops, a pair of display switches respectively controlled by the two flip-flops, a counter controller controlling a light-emitting diode display through a display driver, as switched by the pair of display switches, whereby upon a single clap by a user a time of hours, minutes, and seconds will be displayed, and upon double claps a date of month and day will be displayed, for a convenient time display.