Adobe DC - Simplified field notation won't accept mathematical operation.

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I banged my head on this wall forever...finally I asked my hubby (who is a SharePoint developer) to look at the form with me... Turns out the problem is that there should be an okay button in the JavaScripts dialogue box, and mine didn't show. There might be other things you could do (I read a forum that suggested changing the size of Adobe's native JavaScript editor box), but what the hubby and I did was switch to the Notepad as the JavaScript editor.

In Adobe choose edit, then preferences, highlight JavaScript on the left, and then click the "Use External Javascript Editor" Button, in the windows explorer dialogue box, locate your C drive>Windows folder>System32 folder>then scroll down beneath the sub folders to the notepad and highlight it, and click open), I then returned to the simplified notation option in the forms field properties, and entered my simple notation (Field1-Field2), and then chose save in the notepad editor in the file drop down menu, and GLORY HALLELUJAH...it worked.

Hope this helps.

Try putting a space between the values and the operator. If that doesn't work just use a custom calculation script:

event.value = Number(this.getField("GrandTotal").value) / 488;