Important Notice
The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
Serial Numbers
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A serial number is a date/time code used by BASIC to represent dates and
times between January 1, 1753 and December 31, 2078.
■ Numbers to the left of the decimal point represent the date;
numbers to the right of the decimal point represent the time. For
example:
This serial number Represents this date
══════════════════ ═════════════════════════
20323.25 August 22, 1955 6:00 AM
20324.25 August 23, 1955 6:00 AM
367.5 January 1, 1901 12:00 PM
367.75 January 1, 1901 6:00 PM
■ A serial number with no fractional part represents a date only. A
serial number with only a fractional part represents a time only.
■ The date portion of the serial number (to the left of the decimal
point) can represent dates ranging from January 1, 1753, through
December 31, 2078. Dates before December 30, 1899 are represented
by negative numbers; dates after December 30 are represented by
positive numbers:
This serial number Represents this date
══════════════════ ════════════════════
-1 December 29, 1899
0 December 30, 1899
1 December 31, 1899
2 January 1, 1900
■ The time portion of the serial number (to the right of the decimal
point) can represent times that range from 0 (00:00:00 AM) to
.99999 (11:59:59 PM or 23:59:59).
The following date/time functions return a serial number value:
◄DateSerial#► ◄Month&► ◄TimeSerial#► ◄Hour&►
◄DateValue#► ◄Weekday&► ◄TimeValue#► ◄Minute&►
◄Year&► ◄Day&► ◄Now#► ◄Second&►