Formulas and Functions

An important feature of the Excel spreadsheet program is that it allows you to create mathematical formulas that will automatically calculate results. Otherwise, it is not much more than a large table for displaying text.

Formulas

A formula is an equation that makes calculations based on the data in your spreadsheet. Formulas are entered into a cell in your worksheet. They must begin with an equal sign, followed by the addresses of the cells that will be calculated upon, with an appropriate operand placed in between. Once the formula is typed into the cell, the calculation executes immediately. The formula itself can be viewed in the formula bar

In the example below, a formula has been created for calculating the subtotal of a number of textbooks. This formula multiplies the quantity and price of each textbook, and then adds the totals to give the combined cost of all books.

Linking Worksheets

It is possible to create a formula that uses data from two different worksheets, as long as these worksheets are within the same workbook. The base formula is written as "sheetname!celladdress". For example, the value of cell A1 in Worksheet 1 and cell A2 in Worksheet 2 can be added using the formula "=A1+Sheet2!A2".

Relative, Absolute, and Mixed Referencing

Calling cells by just their column and row labels (such as "A1") is called relative referencing. When a formula contains relative referencing and it is copied from one cell to another, Excel does not create an exact copy of the formula. It will change cell addresses relative to the row and column they are moved to. For example, if a simple addition formula in cell C1 "=(A1+B1)" is copied to cell C2, the formula would change to "=(A2+B2)" to reflect the new row.

To prevent this from happening, cells must be called by absolute referencing. This is accomplished by placing dollar signs "$" within the cell addresses in the formula. Continuing the previous example, the formula in cell C1 would read "=($A$1+$B$1)" if the value of cell C2 should be the sum of cells A1 and B1. Both the column and row of both cells are absolute and will not change when copied. Mixed referencing can also be used where the row OR column is fixed, but not both. For example, in the formula "=(A$1+$B2)", the row of cell A1 is fixed and the column of cell B2 is fixed.

Basic Functions

Functions can be a more efficient way of performing mathematical operations than formulas. For example, if you wanted to add the values of cells D1 through D10, you would type the formula "=D1+D2+D3+D4+D5+D6+D7+D8+D9+D10". A shorter way would be to use the SUM function and simply type "=SUM(D1:D10)". Several other function commands and examples of functions are given in the table below:

The Function Wizard

Excel has menus of other available functions that can be accessed using the Function Wizard. To select a function using the Function Wizard, follow these steps:

1. Click the cell where the function will be placed.
2. Click the Insert Function button on the Formulas tab. The Insert Function dialog box will open.
3. Select a function category from the Category dropdown menu.
4. Select the type of function from the Select a function scroll-down menu. A description and example of the function will appear below the menu.
5. Click OK. The Function Arguments dialog box will open.
6. Choose the cells that will be included in the function.
7. When all the cell values for the function have been entered, click OK.

Autosum

Use the Autosum function to add the contents of a cluster of adjacent cells.

1. Highlight the group of cells that will be summed (cells B2 through G2 in this example).
2. Click the Formulas tab.
3. Click the Autosum button.
4.