How do I code the following: Select from a combo box, each item has a value, the value reflects in a different filed. If there is nothing selected then the value in the field must be 0?

Thanks Nick, perfect, however, when I select one of the other items on the combobox with a values then the "Council Reg" revert back to "0" - how do I select more than one and still keep the value of the already selected value in their fields ? If I select "Council Reg" then the value in the field is 1200, plus then I selct WPTP 1 with a vaue of 2000 in a diferent/next field. This gives me a total value of 3200. (I have about 6 posible items to select from. (this is my first time using Ninox, with no coding knowlage, so forgive the ignorance)