Date-Time Calculations

Giganews Newsgroups
Subject: Date-Time Calculations
Posted by:  Three Lefts (spamtrap@spamtrap.invalid)
Date: Mon, 14 Jul 2008

I need to create a little spreadsheet to calculate dates for drug

The two inputs are (1) the date & time when the test was taken and (2)
the time period that the test covers. The output is the date when the
test coverage starts.

That's simple except that the units vary. Some tests are good for
hours and others for days. One test can detect alcohol usage for 80
hours. Another can detect drug use for 90 days.

If the test duration units are hours, something like this will work:

        A                        B                          C  D  E
1  7/08/08 9:15 am    Timestamp when test was taken
2                80    Test duration (hours)
3  5/05/08 1:15 am    Timestamp when test coverage begins

A1 & A3 are formatted as date & time.

The formula in A3 is "=B3-(B4/24)".

I would appreciate suggestions for a way to put a value in A2 that can
be in hours or days and maybe in months.

My alternative would be to create two tables in the same spreadsheet:
one for hours and one for days.