First, I know with SELECT CASE you want to start with your smallest possibility with "IF VAR < VAL THEN" type statements. You have largest listed first. If your code executes in order, then you will be changing your OutputDividerBox.Text value with each successive IF... clause.

Secondly, to work with decimals in PBP, multiply it by 10 or 100 up front, then divide the result back down by the same 10 or 100 at the end. Example:

7.5 X 22 = (75 X 22) / 10

That would allow you to work with decimals in PBP. Of course, you need a filter to tell you if that's needed (perhaps IF MOD != 0 THEN). I'm sure there are other aspect that need attention, but these were the obvious things I could contribute towards.