The Excel ISBLANK function returns TRUE if cell value is blank and False if the cell is not blank, and it is also an information function.

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

Excel has over 475 formulas in its Functions Library, but we've selected the most popular, from date and time functions to mathematics and simple data manipulation.