@DocE

Why do you use 'Let' ??

Code:
sub M_snb()
  cells(1,12)="170.110.000."& choose(instr("FHSV",left(cells(1,6),1)),"415015","415025","415030","143015")& ".0000.0000.000.000"
end sub
PS.
- most of the time multiple ifs can be replaced by an algorithm that reflects an underlying pattern.
in this case e.g. "4150" & 5*instr(" F HSV",left(cells(1,6),1))
- It might be worthwhile to study systematically every function in Excel, starting with text, information, etc.