You can pull in a contact's first and last name into a Lua script to use in any form calculations.
To access these fields, simply type contact.first_name
or contact.last_name
into the Script box of your form.
This will look up the contact that you are currently filling out a form for. Note: if you use these fields in a Contact Form, when you create a new contact, you will not be able to access these fields until you create the contact first!
These fields are string text fields, so you can perform a number modifications on them to perform the calculations that you need. Check out our article on modifying strings.