Passing computed values from one form to another

Hi. 

I reviewed similar questions on the forum but I am not sure they apply to my specific need. 

Users are completing an enrollment form. For one of the questions, "Voluntary Long-Term Disability Insurance" (towards the end of the form), in order to make it easier for the user to enter the correct amount in the "LTD Premium" field, I supply a link to a separate form ("LTD Premium Calculator") where the user can have the correct amount calculated for them; it gets displayed in the "Your semi-monthly premium" field. I would like that computed value to be automatically transferred back to the "LTD Premium" field on the enrollment form. Is that possible?

If this has already been answered elsewhere, please direct me to the appropriate forum response.

Thanks!