The SUM Function

A common task in building spreadsheets is summing a row or column of numbers. Excel comes with a built-in formula for quickly tabulating sums of columns and rows.

The SUM formula can be reached using a single mouse click on the summation toolbar icon. The steps for doing so look like the following:

1. Select where you want the sum to be by placing the cursor on that location.
2. Click the summation icon. Excel will show you what range of numbers it thinks you want to add up. Modify this range as necessary.
3. Press the Enter key to signal that you have completed the formula.

Excel has several hundred functions built into it.  You can reach most of these through the Paste Function dialog box.  Click on the Paste Function toolbar icon to reach it. For more information refer to the toolbar presentation.

Each Excel function has a standard format.  For the Sum function, the format looks like the following:

=SUM(B3:B6).

Here's how to translate:

The = tells Excel that a formula is coming.

SUM identifies which function is being used.

The range in parentheses (B3:B6) describes the arguments used by the function. In other words, it tells Excel what parts of the spreadsheet to use and what to do with each location that is identified.

For the Sum function, the arguments describe the range of spreadsheet cells that need to be added up. For other built-in functions, the arguments are more complex.

Learning how to use any built-in function consists largely of understanding its arguments and what they do. The Excel help files are very useful for this -- once you know what to plug in where, functions rapidly lose their mystery.