Problem

Source: Iran MO second round 2024 P1

Tags: number theory, combinatorics



Kimia has a weird clock; the clock's second hand moves 34 or 47 seconds forward instead of each regular second, at random. As an example, if the clock displays the time as $\text{12:23:05}$, the following times could be displayed in this order: $$\text{12:23:39, 12:24:13, 12:25:00, 12:25:34, 12:26:21,\dots}$$Prove that the clock's second hand would eventually land on a perfect square.