Matt your a feckin genius!
It works perfect, thank you very much. I would honestly never in a million years worked that out, I've honestly been reading shitloads about Roundup/Ceilings/Floors/etc etc.
Didn't have a clue what to do next.
Thanks a lot, really appreciated.
PS. Attached a test Spreadsheet to show the calculation for the future, if anyone is needing it (unlikely I know)