' Fun with VBA / MS Excel!

Private Sub CommandButton1_Click()
Dim mark As Integer, grade As String

mark = Int(Rnd * 100)
grade = "F"

If mark <= 20 Then
grade = "F"
ElseIf mark <= 40 Then
grade = "E"
ElseIf mark <= 60 Then
grade = "D"
ElseIf mark <= 80 Then
grade = "C"
ElseIf mark <= 90 Then
grade = "B"
Else: grade = "A"
End If

Cells(1, 1).Value = "Mark:"
Cells(2, 1).Value = "Grade:"

Cells(1, 2).Value = mark
Cells(2, 2).Value = grade

End Sub