You've seen how calculations work, and what the Specify Calculation dialog looks like (refer to Figure 7.4). Now it's time to actually create a calculation. This is a step-by-step walkthrough; in Hour 8, you'll find more details on the specific types of functions available to you.
The Expense Report template has a database field called Rate per Mile. It is used to calculate the reimbursement for an employee's use of a car based on a rate of 28 cents a mile. If you enter the number of miles driven, the database calculates the appropriate reimbursement. The field is defined as an auto-enter field; you can modify it for any record in the table if you want to use a different value.