As you might guess, one of the domains in which Microsoft Excel really excels is finance math. Brush up on the stuff for your next or current job with this how-to. In this tutorial from everyone's favorite digital spreadsheet guru, YouTube's ExcelIsFun, the 2nd installment in his "Excel Finance Trick" series of free video lessons, you'll learn how to use the FV function. See the math formula for calculating future value and for calculating the effective interest rate. Also see long hand how compound interest is calculated. See that Excel only sees 15 significant digits in Excel.