How do I go about calculating expiration times and dates in Excel 2003? For
instance:


Start: 1/1/2009 1600 + 36 hours = EXP: 1/3/2009 0400

I would like to have Excel automatically calculate the expiration time and
date from the start time by referencing a value in another cell. That cell
would contain a drop down list of different values. In short, the user would
enter the start date and time, choose a value from the drop down list, and
Excel would automatically calculate the EXP time and date.