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Tests I just ran on a form of mine indicate that substituting normal textboxes for the number controls currently used for fields A and B will yield better results but only slightly better, in that if only a zero is entered in A or B, C will show whatever is in the other box. However, just like with the "number" controls, if either box A or B is empty, C will be empty too.
Our calculation feature is still under development and currently the best way I can think of to achieve the functionality you want would be to copy the form's full source and paste it into the body of a web page along with a script to perform the calculation. We could do the script for you.
okok! thank you very much
how can i do
From the screenshots in your other thread about this issue, it appears that your only requirement is that is if just a zero (0) is entered in either A or B, C should show a result and you don't mind if C remains blank if either A or B contains nothing. If that's the case, there's no need to embed the form anywhere. Just deleting fields A and B and replacing them with textboxes will suffice:
If you would like further help with this, please let us know.