Have you ever wanted to subtract one date from another? Or find out how many workdays until vacation? Or maybe you need to figure out a project end date. You can do all of this and more by using date functions in Excel formulas. As long as you type a date in a format that Excel recognizes: 8/22/2011, 22-August-2011, or August 22, 2011, for example, Excel will interpret the date as a serial number, and you can use formulas to find important dates. For example, you can then use formulas to subtract...