# Formula

A **formula** is an expression telling the computer what mathematical operation to perform upon a specific value. When referring to computer software, formulas are most often used in spreadsheet programs such as Microsoft Excel. In the picture below, is an example of a Microsoft Excel formula **=SUM(A$1:A$3)**, which adds the total of cells A1,A2, and A3. In this formula SUM is the function of the formula.

Tip: Press the shortcut key **Shift + F3** to open the Excel Formula or Insert Function window.

Note: A formula will not be seen unless the cell is selected.

## Related pages

- Help, examples, and information on Excel formulas.
- Getting #DIV/0! in Microsoft Excel spreadsheet.
- Type an equal sign in a spreadsheet without doing a formula.
- Microsoft Excel help and support.

**Also see:** Absolute cell reference, Autosum, Formula bar, Lookup, Range, Relative cell reference, Sum, Whatif