are one of the most useful and well used features in Excel. Formulas can be used to perform basic number crunching, such as addition or subtraction, as well as more complex calculations such as payroll deductions or averaging a student's test results. Using formulas effectively is central to getting the most out of any spreadsheet program.
Writing formulas is really quite easy to do. All you need is an understanding of how they work and the steps that you need to follow each time you create one.
Read the Excel Formulas Step by Step Tutorial
to learn the basics of creating formulas in Excel.