Sub IsAlphaNumeric()
Dim rng As Range, cel As Range
Set rng = Range("G2", Range("G" & Rows.Count).End(xlUp))
For Each cel In rng
If ContainsNumber(cel.Value) And Not WorksheetFunction.IsNumber(cel) Then
cel.Offset(, -3) = "B"
Else
cel.Offset(, -3) = "S"
End If
Next
End Sub
Private Function ContainsNumber(celValue As String) As Boolean
Dim a As Integer
For a = 1 To Len(celValue)
If IsNumeric(Mid(celValue, a, 1)) Then
ContainsNumber = True
Exit Function
End If
Next a
End Function