Sub Macro()
Dim rng As Range
Dim rngText As String
Dim i As Integer
Dim arrtext() As String
rngText = "B6,B7,B8,B10,C6,C7,C8,C10"
arrtext = Split(rngText, ",")
Set rng = Sheet1.Range(arrtext(LBound(arrtext)))
For i = LBound(arrtext) + 1 To UBound(arrtext)
Set rng = Union(rng, Range(arrtext(i)))
Next i
MsgBox rng.Address
End Sub