1] Add days directly If the expiry period is defined in days, you can calculate the expiry date by simply adding the number of days to the starting date using the + operator.

Learn how to calculate the Simple Interest in Excel either for a single entry or a range or entries, between two dates, using this forumula.

You should have experience with Excel before trying to use formulas to calculate what day of the week the 15th of a given month is, and you have several options to do this.

Since each date is really just a number stored in Excel, to compute the midpoint of two dates you would use the same mathematical formulas you would use to calculate the midpoint of two numbers ...