Calculations are not supported in Formscentral forms at this time. This can be done with PDF forms but not HTML forms.
FormsCentral does not support formulas in the forms. You can add them to the View Responses tab. Documentation on available formulas is at http://helpx.adobe.com/acrobat-com/formscentral/help/formula-syntax-built-in-functions.htm l.
Thank you so much for your help!
Thank you Andrew