One of the most important spreadsheet functions is using formulas to calculate values in cells (so one cell can be defined, say, as the sum of two others minus a third cell). When the values that make up a formula change, the cell that contains the formula's total value is automatically recalculated. These steps work for Microsoft Excel 97.

- Skill level:
- Moderate

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### Things you need

- Excel Book
- Microsoft Excel

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## Instructions

- 1
Start Microsoft Excel and open the file you want to change.

- 2
Double-click on the cell where you want the total to appear.

- 3
Press the = key on the keyboard. This tells Excel that you are entering a formula into the cell.

- 4
Enter the formula, then press Enter. Follow the steps below for an example.

- 5
Enter an opening parenthesis character: (.

- 6
Enter a cell name. For example: =(E2.

- 7
Press the + key.

- 8
Enter another cell name and a closing parenthesis character: ). For example: =(E2+E3).

- 9
Enter a minus sign and a third cell name. For example: =(E2+E3)-E4.

- 10
Press the Enter key to accept the formula. The cell will display the sum of the first two cells minus the third cell.

#### Tips and warnings

- Formulas are just equations. Instead of adding or subtracting numbers you are adding and subtracting the contents of a cell.
- Excel includes a number of predefined functions to use as well. You can combine the predefined functions into your own formula. (See "How to Use Provided Excel Formulas.")