You build a formula by making reference to other cells. For instance, to display the total of two cell values in a third cell, you would put the formula (location of cell 1) + (location of cell 2) in the third cell. When the contents of cell 1 or cell 2 change, cell 3 is updated to reflect the change.
Formulas are entered in the active cell just as you enter text or values. However, you always start a formula with an equals sign (=).
Note: You can begin a formula with other operators if you like, for example "+" or "-".
Now you’re ready to build the formula. Lets use an example of adding cell A1 and A2 together and putting the result in cell A3. First, click on A3 and type "=". Next, click on cell A1, type "+" and then click on cell A2. Note that the formula bar will read:
=A1+A2
You can type the entire formula directly if you want. Often though, you’ll find it easier to refer to a cell in a formula by simply clicking on it.
When you have finished the formula, click on the Confirm button on the status bar, or press enter, and the results of the calculation will be inserted into the active cell.
If you make mistakes while you’re building a formula and you want to start over again, press esc or click on the Cancel button on the formula bar. Spreadsheet erases the formula and you can start again by entering an equals sign.
If you want cells to show their formulas instead of the results, open the View menu and click on the Formulas command. When formulas are showing, this command has a check next to it. To show results again, click on the command to remove the check.
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