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.

Excel's data validation feature is more versatile than you might think. Learn how to use literal values, input values, list values, and even formulas to restrict input date values using data ...

I've got an Excel 97 worksheet in which I need to validate some cells. No problem, I'll just use Data->Validate, right? Wrong. The built in validation works well enough as long as the user doesn't ...