Private Sub CommandButton1_Click()
Dim C As Range
For Each C In Range("tab")
If C.Offset(0, 7) = "" Then
C.Offset(0, 7).FormulaR1C1 = "=RC[-3]/RC[-6]"
C.Offset(0, 7) = Format(C.Offset(0, 7), "##.00%")
End If
If C.Offset(0, 8) = "" Then
C.Offset(0, 8).FormulaR1C1 = "=RC[-4]/RC[-8]"
C.Offset(0, 8) = Format(C.Offset(0, 8), "##.00%")
End If
Next C
End Sub