> So there are 24 hours in a day, 1440 minutes in a day and 86400 seconds in the average day. This is incorrect. There are EXACTLY 60 seconds in a minute, EXACTLY 60 minutes in an hour, and EXACTLY 24 hours in a day (EXACTLY 1440 minutes in a day and EXACTLY 86400 seconds in a day). EXACTLY. ALWAYS. EVERYTIME. WITHOUT EXCEPTION. This indeed applies for the average day because it applies exactly to every day. Since every day is exactly always 86400 seconds long, the average day is also exactly 86400 seconds long, however, there is no day that is any length OTHER THAN 86400 seconds exactly. Only the co-ordinated time is loosey goosey because it is based on an approximation of the length of second holding the duration constant, rather than the length of a second being based on being exactly 1/86400 of a day (and thus variable in length).