Follow the steps / instructions below:
1. In PDF Studio, go to the “Forms” tab and click on Text Field
2. Create two text fields called A and B.
3. Right click on field B and select Properties
5. Click Calculate and select “This field has a custom calculations”
6. Put the following script under text box:
7. Hit OK
8. Exit form editing (by clicking on the Home Tab)
9. Start testing the calculations.