Our current civil time is based mostly on the numbers "12" and "60", dating back to the duodecimal and sexagesimal systems used by
the ancient Babylonians, instead of the decimal systems of time
used in China.
Although the whole world now uses decimal metric units for almost every other quantity, we still use hours and minutes instead of
metric time units such as kiloseconds or megaseconds, and we still divide days into 2 halves by 12 hours
by 60 minutes by 60 seconds, and multiply them with weeks of 7 days, months of 30 or 31 days (or 28 or 29) and years of 12 months.
It is difficult to make time calculations involving standard units, which is why scientists and computer programmers convert dates
and times to decimal time units.
Types of Decimal Time
French Revolutionary Time divided the day into ten hours, each hour into 100 decimal
minutes, each minute into 100 decimal seconds, with ten-day weeks, introduced in France in 1793
Fractional days are decimal times of day expressed as a decimal fraction, obtained by
dividing the number of hours by 24, which are added to decimal dates and other dates by astronomers and computer programmers
Swatch Internet Time is a proprietary decimal time standard from the Swiss watch company
which counts 0.001 fractions of a day, called ".beats"