As you might guess, one of the domains in which Microsoft Excel really excels is business 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 8th installment in his "Excel Business Math" series of free video lessons, you'll learn how to work with whole and decimal numbers. See how to write words to represent numbers (for checks). See how formatting can hide decimals.