What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
If you are referring to how to do calculations in certain fields, please follow:
You will have to log in to your JotForm form builder and click on conditions:
And than select update/calculate field:
New window will open where you can specify how your calculations will work:
You can define how the calculations will be done conditioning the fields that you define as well, of course you can define multiple fields to be conditioned, and you can make several of these conditions for your form.
Please let me know if that helps or if you have more questions.