Formulas, of course, are what make a spreadsheet a spreadsheet. If it weren't for formulas, your worksheet would just be a static document - something that could be produced by a word processor that has great support for tables.
Excel has a huge assortment of built-in functions, has excellent support for names , and even supports array formulas (a special type of formula that can perform otherwise impossible calculations).
A formula entered into a cell can consist of any of the following elements:
Operators such as + (for addition) and * (for multiplication)
Cell references (including named cells and ranges)
Numbers or text strings
Worksheet functions (such as SUM or AVERAGE)
A formula in Excel 2007 can consist of up to 8,000 characters . After you enter a formula into a cell, the cell displays the result of the formula. The formula itself appears in the formula bar when the cell is activated.