Private Sub Command1_Click()
    Dim m As Integer
    Dim n As Integer
    Dim s As Long
    Dim i As Integer
    m = Val(Text1.Text)
    n = Val(Text2.Text)
    s = 0
    'For i = ?  To n
        't = ?
        's = s + ?
    Next
    lblResult.Caption = s
End Sub
Private Function f(ByRef x As Integer) As Long
    Dim t As Long
    t = 1
    For i = 1 To x
        't = ?
    Next
    'f = ?
End Function