Whether you're new to Microsoft® Excel® or a regular user, you'll soon realize that it's more than just a grid in which you enter numbers in columns or rows. You can use Excel to find totals for a column or row of numbers, but you can also calculate a mortgage payment, solve math problems, or create a best and worst case scenario based on variable numbers that you plug in. Excel quickly and easily does this by using formulas in cells. A formula performs calculations or other actions on the data in your worksheet. A formula always starts with an equal sign (=), which can be followed by numbers, math operators (such as a plus or minus sign), and functions, which can really expand the power of a formula.