To mess with our heads is probably the real reason.
The code on the page works out a duration in days, say like 2.222199999999999
Where 2 is the days and the .222... is a fraction of a day.
Then is works out the hours, minutes, seconds and thousands of a second of that fraction of a day to display.
When the seconds bit is worked out you should have 0-59 seconds,
There are 3600 seconds in a hour but the code uses 360 instead.
So the 'seconds' are a factor of ten out, 59 = 5.9, 58 = 5.8 etc down to 1 second = 0.1
the 'seconds' are then rounded down for the counter display, 5.9 rounds down to 5 etc, so it displays 5, 4, 3, 2, 1, 0.