Sub T_278()
    If Not IsNumeric(ActiveCell.Value) Or ActiveCell.Value = Empty Then
        ActiveCell.Interior.Color = vbYellow
    Else
        Select Case ActiveCell.Value
        Case Is > 0
            ActiveCell.Interior.Color = vbGreen
        Case Is < 0
            ActiveCell.Interior.Color = vbRed
        Case Is = 0
            ActiveCell.Interior.Color = vbBlue
        End Select
    End If
End Sub