Hi Scott
basically, because Excel stores dates as numbers -
.... taken from help
***
Microsoft Excel stores dates as sequential numbers which are called serial
values. By default, January 1, 1900 is serial number 1, and January 1, 2008
is serial number 39448 because it is 39,448 days after January 1, 1900.
Excel stores times as decimal fractions because time is considered a portion
of a day.
Because dates and times are values, they can be added, subtracted, and
included in other calculations. You can view a date as a serial value and a
time as a decimal fraction by changing the format of the cell that contains
the date or time to General format.
***
Cheers
JulieD
