Mutiply textfield by value when checkbox is check

Question

Hello all,
I have a fillable PDF Form, built in Adobe Acrobat Pro X, that I am creating as a repair form with charges included in it.
I know how to have a value filled in a given text field when a checkbox is checked.
My question is this.  Say I have a textfield labeled as "labor_hrs" that is set to a number format.  What I want to do is to have this box multiplied by a given value of 45.00 populated to the "labor_chrg" text field.  I can get this feature to work on its own.
What I want to do is only have the value populated to the "labor_chrg" when the checkbox labeled "billable" is checked.
Any help would be appreciated.

Answer 1

A quick way is to set the export value of the "billable" check box to 1.
You can then use the simplified field notation script of:
(labor_hrs * 45) * billable
A custom JavaScript calculation:
function GetField(cName) {
// return field object with error checking;
var oField = this.getField(cName);
if(oField == null) app.alert("Error accessing field " + cName, 0,1);
return oField;
} // end GetField function;
event.value = (isNaN(GetField("billable").value) == false) * GetField("labor_hrs").value * 45;
If you add a hidden field for labor rate called "labor_rate", then you can use the "Field is the product of the following fields:" and select the "billable", "labor_hrs", and "labor_rate" fields.