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.

A TechRepublic member wrote for advice on calculating the years, months, and days elapsed between two dates. This tutorial explains the solution provided by TechRepublic contributor Jeff Davis.

Percentages aren't always easy to calculate, but one of the best tools in Excel's toolbox is calculating percentages for you. Here's how to do it.