Private Sub CommandButton1_Click()
    Dim v_txt() As Variant, c As Variant
    v_txt = Array(Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12)

    For Each c In v_txt
        If Not IsNumeric(c) Then
            c.Value = ""
            c.BackColor = vbRed
        Else
            c.BackColor = vbWhite
        End If
    Next
End Sub