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150 Part II: Using Formulas and Functions
When entering a number or reference to a cell that contains a number or formula
that returns a number for the value_if_true and value_if_false arguments, you simply
enter the value or cell address. When entering text for these arguments, you need to
enclose the text in a set of double quotation marks. And when entering an expression,
you enter the operands and operator or function name and arguments as you would
in any formula.

Constructing Decision-Making Formulas

The biggest use for the IF function is performing conditional operations in a formula,
one set of operations when the IF condition expressed by its logical_test argument is
found to be TRUE and another when it is not. These decision-making formulas can
be one of two types: formulas that perform their computations using alternate values
depending upon the outcome of the condition or those that perform alternate calcula-
tions based on the outcome.

Selecting between alternate values

Figure 12-1 shows an example of the first type of decision-making formula, where
alternate values can be put to good use. The spreadsheet shown in this figure con-
tains a variation of the Tip Lookup worksheet you encountered in Chapter 11. In this
version, the Tip Schedule contains tip amounts for alternate tip percentages (15% in
column C and 20% in column D), and the input section of the spreadsheet contains a
Tip Percentage cell (G2), where the user can specify either a tip percentage of 15 or
20 percent.

Figure 12-1:
The Tip with
alternate
15% and
20% tip
percentages.