Ilan Mitchell-Smith wears a Casio Calculator

In John Hughes's Weird Science (1985), two high-school outcasts, Wyatt and Gary, use a home computer to build themselves the perfect woman and accidentally conjure Lisa, who proceeds to remake their lives. Ilan Mitchell-Smith plays Wyatt, the quieter and more anxious of the pair.

On Wyatt's wrist is a Casio calculator watch, the digital kind with a grid of tiny buttons set into the face for doing arithmetic, clearly visible in close-up as he works at his keyboard. Casio had made the calculator watch a fixture of the early-to-mid 1980s, standard equipment for the technically inclined.