At a glance it just looks amatuerish too. You can see they're constantly checking the cell D2 and switching on whether it falls under a value 1-5 or so. This s

At a glance it just looks amatuerish too. You can see they're constantly checking the cell D2 and switching on whether it falls under a value 1-5 or so. This should be 5 cells calculating an output uniquely for each possible value of D2. Then picking the appropriate one later on.