Bookkeepers, project managers, HR departments and more use the Excel Date & Time functions WEEKNUM, ISOWEEKNUM, WORKDAY, WORKDAY.INTL to calculate time. Here's how.

DATEDIF(), which means Date + Dif, is a compatibility function left over from Lotus 1-2-3 that Microsoft adopted in Excel version 2000. It's fallen off current Excel menus, but you can still use ...