Working with dates in Excel is a common task:

• Are you trying to determine the number of days between two dates?
• Do you need to know the date that is X number of days in the future?
• Do you want to find out how many work days there are before Christmas, or until you retire?

Date formulas in Excel can be extremely useful in a variety of projects - large and small alike. In this series of Office for Mere Mortals articles we have a look at some of the basic date formulas and how to combine them to create more powerful date-based functions. But to start, we'll have a look at how dates and times are stored in Excel.

Excel tries to hide the technical workings from you - but when things go awry you'll be able to fix it easily if you understand what happening.