Use the Summary and Discounts section to add items to the payment summary of your order form, multiple your items with a Quantity, add discounts and also markups. The total that will be displayed in the Payment Summary table represents the amount that form users will have to pay you after submission.
Note: The Calculate button will appear only when at least one merchant is enabled for the form in the Payments section.
Upon customizing the Payment Summary table, you can change the label names of your items (as shown in the summary), show the quantity value for each selected item and the detailed formula (if used).
Formulas are the ones you manually set up under the Assign Values or Formulas to Fields subsection, by using Number fields on your order form with numericplus validation.