The Calculate tab appears in the Properties dialog boxes for only text boxes and combo boxes. Use these options to perform mathematical operations on existing form-field entries and display the result.
Select this if you want the user to type.
Select this to make further options available:
Lists the mathematical functions to apply to the selected fields. Choose Sum to add the values entered in the selected fields, Product to multiply them, Average, Minimum, or Maximum.
Opens a dialog box with a list of the available fields in the form that you select to add or deselect to remove from the calculation.
Uses JavaScript with field names and simple arithmetic signs. The Edit button opens a dialog box in which you can write, edit, and add scripts.
Displays any custom scripts you have added for calculations. The Edit button opens a dialog box in which you can write and add new JavaScripts.