For Next + Range("A2:G2") + Call mysub

Hell all users !! I am a new user so i salute everyone. This forum seems full like the old MS forum..!!

i have a little question , probably easy..
i make this and it works fine....

Dim aWB As Workbook
Dim aWS As Worksheet
Dim i As Long
Set aWB = ThisWorkbook
Set aWS = aWB.Worksheets("Main")
For i = 4 To 80 Step 4
aWS.Range("D" & i).Value = (aWS.Range("H7").Value - aWS.Range("C" & i).Value) / aWS.Range("O4").Value
aWS.Range("B" & i).Value = (aWS.Range("G7").Value - aWS.Range("A" & i).Value) / aWS.Range("O4").Value
Next


but...what if i would like to indicate a range...like this (syntax not working!) .....aWS.Range("A" & i : "H" & i).CalculateRowMajorOrder ???
and if i want to call a sub inside the For Next .. would it be possible to propagate the > i < to the called sub ???

Thanks who can help !! Please if anybody knows if excel-dna can multithread a for next ..tx !
Paolo