Anthony Michael Hall wears a Casio Calculator

John Hughes's The Breakfast Club (1985) puts five high-school students through a Saturday detention, each introduced as a type before the film complicates them. Anthony Michael Hall plays Brian Johnson, the academic one, and the calculator watch on his wrist is part of how the film signals that at a glance.

The watch is a Casio calculator, the digital model with a tiny keypad set into the face for doing sums on the wrist. Casio had made calculator watches a fixture of the early 1980s, and they were standard equipment for the kind of student who actually used the calculator. The film never names or lingers on it, but it stays on Brian's wrist through the detention.