Youform allows you to add custom variables to your forms for advanced calculations and logic. By default, Youform provides two system variables: price and score, but you can add your own custom variables as well. Here's how:
Go to your form from your dashboard, then click on the settings tab. On the side panel, you will find hidden fields and variables. Click on that.
Then check the variable section, and type the variable name you want to put. You can also select the type (text or number) depending on what value holds in that variable, and then hit add to proceed.