CPUs in cameras must use algorithims to determine these things and display them in fractions that are meaningful to people, hence the 32 seconds shifted to 30 seconds. When you get into time exposures though, a 2 second difference in a 30 second exposure is of little consequence.

Still, these stupid fractions coming from digital cameras these days are unfamiliar to everyone, for example, 1/640 s, as my camera displays. What is that? Why not go into normal engineering notation and present it as 1.56 ms (milliseconds) and start people down the path of learning about units? But then they would probably round it to 1.5 ms and we'd be right back where we began, almost.

Wayne