Excel’s Date & Time functions ease the workload for bookkeepers, project planners, HR departments, and other jobs where time is money. The four functions covered here—ISOWEEKNUM, WEEKNUM, WORKDAY, ...

Microsoft Excel handles dates as numbers, even though they display as dates -- for example, the date "10/10/2011" is really stored as "40826." This makes it difficult to directly add or subtract years ...