How to do math between two variables in Visual Basic

        Select Case lstFlavours.SelectedItem
            Case "Vanilla" Or "Chocolate" Or "Strawberry"
                scoopType = BASIC_FLAVOUR
            Case "Mango" Or "Bananna" Or "Grape" Or "Mint Chocolate Chip"
                scoopType = PREMIUM_FLAVOUR

                scoopType*txtScoops = runningTotal 

        End Select

I would like to do the math with the scoopType * txtScoops which is the number of scoops i have, and add it to my running total