Given that the stopwatch records times to the nearest thousandth of a second, it means that the time recorded will be given at 3 decimal places.
To get the time in the nearest tenth of a second, we would first convert to the nearest hundredth of a second, at this, the reading of 25.453 seconds will be
= 25.45 seconds
Since the number at the hundredth position is 5 (or more), we would add 1 to the number at the tenth position to round it to the nearest tenth. Hence the reading to the nearest tenth