Simple Calculations

Instructions: You will just use the keyboard for this exercise.

Comment: To demonstrate the power of Excel in calculations we shall build calculations up from the simple ones to more complex ones.

=13+26+22

Note two things about this formula:
it starts with an equals sign. All formulae must start with this.
it consists of numbers separated by a mathematical operator. The operators allowed are + (plus), - (minus), * (multiple), / (divide) and ^ (raise to a power).

Now press <Enter>. The formula is calculated and the result, 61, is displayed in the cell. However, note that the formula bar just above the worksheet still contains the text =13+26+22.

Spreadsheets work on two layers - the stored layer and the displayed layer. The stored layer literally contains just what you type in. It is the 'nuts and bolts' of the spreadsheet. All numbers are stored in the same way, text is stored as simple ASCII characters and formulae are stored exactly as they are typed in. The formula bar will always show you what is in the stored layer.

The displayed layer is what you see on the worksheet. The displayed layer calculates formulae and displays the result. The displayed layer adds formatting to numbers so that you see them with 2 decimal places, displays them as dates or adds currency symbols. Text can be altered in terms of what font, size and style it is displayed in. By default the worksheet shows you what is in the displayed layer.

Activity 4.2 The disadvantage of the formula entered in the previous exercise is that it doesn't take account of changes in the data. We will now set up a formula that does. Select cell F6 and type in the following:

=C6+D6+E6

This formula effectively says "Add the contents of cells C6 and D6 and E6". This means that should the contents of cell C6 change, the result of the formula will change as well. Press <Enter> to complete the formula. The cell will display the result, 74.

Now select cell C6 and change the number to 36. Press <Enter>. Immediately the result in cell F6 changes to 84 taking account of the change in data. This would not have happened if the numbers were just typed in.

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