Formula in CheckBox. Is it poosible ?

Is it possible to write a formula for “CheckBox” column “Value for cheked”?
A simplified example:
Drop-down menu (ID: DBM) choice 1 or 2
Checkbox (ID: CB) “Value for cheked” formula: IF(DBM=1, 100, 200)
“Value for uncheked”: 0
Result (ID: REZ): IF(DBM=1, 5000, 6000)+CB
If selected DBM = 1, the result is 5000+100=5100 if DBM = 2, result is 6000+200=6200

I tried to create an invisible “Output” formula (ID: REZ), where REZ is IF(DBM=1, 100, 200), and CB “Value for cheked” I specify REZ, but with no luck.

What are the proposals?

http://wordpress.org/extend/plugins/jazzy-forms/