Early in the 90s, the NHL and NBA mandated the use of clocks that could measure tenths of a second. So instead of counting down :03, :02, :01, :00, it would go :02, :01, and then 0:00.9, 0:00.8, etc. to 0:00.0.
My question is, does this add one second to each period now? I mean, it used to go straight from :01 to :00 and :00 means buzzer, end of period, right? But now a team could call a timeout or have a stoppage of play with say, 0:00.8 on the clock, where when tenths aren’t measured, this would show up as :00 and mean that it’s over. So are NBA and NHL games 4 and 3 seconds longer now, respectively?
my guess would be that the clock internally counted the final second by tenths, but did not display it. Therefor 0.5 seconds left would still be displayed as 1 second
Before, when there was one second left in the time being measured, the clock turned from 0:02 to 0:01. One second later, it turned to 0:00, the end of the game/period/quarter. At that time, the allotted time had completed.
Now, when there is one second left, the clock turns from 0:02 to 0:01 (actually, in most such situations, it turns from 0:01.1 to 0:01, but ignore that for a moment). Then, one tenth of a second later, it turns to 0:00.9. When it finally reaches 0:00, once again, as before, the allotted time has lapsed.
Now, before they showed the tenths, what happened if you called timeout with five-tenths of a second left? The clock showed 0:01. This wasn’t a problem, though one had to try and estimate the actual time left within which to attempt further play.
In short, 12 minutes is 720 seconds no matter how you represent it on the clock. But keep in mind, the clock doesn’t turn from 12:00 to 11:59 until one second has elapses after turning on the clock.