private void BtnCalcular_Click(object sender, EventArgs e)
        {
            if (TxtNombre.Text.Trim().Length == 0)
            {
                POO.MsgWarning("El Campo Nombre es Requerido.");
                TxtNombre.Focus();
                return;
            }
            if (TxtExamen1.Text.Trim().Length == 0)
            {
                POO.MsgWarning("El Campo Nota Examen 1 es Requerido.");
                TxtExamen1.Focus();
                return;
            }
            if (TxtExamen2.Text.Trim().Length == 0)
            {
                POO.MsgWarning("El Campo Examen 2 es Requerido.");
                TxtExamen2.Focus();
                return;
            }
            if (TxtExamen3.Text.Trim().Length == 0)
            {
                POO.MsgWarning("El Campo Examen 3 es Requerido.");
                TxtExamen3.Focus();
                return;
            }
            if (TxtAcumulativo.Text.Trim().Length == 0)
            {
                POO.MsgWarning("El Campo Acumulativo es Requerido.");
                TxtAcumulativo.Focus();
                return;
            }

            LsbNombreE.Items.Add(TxtNombre.Text.Trim());
            LsbNot1.Items.Add(TxtExamen1.Text.Trim());
            LsbNot2.Items.Add(TxtExamen2.Text.Trim());
            LsbNot3.Items.Add(TxtExamen3.Text.Trim());
            LsbAcumulativo.Items.Add(TxtAcumulativo.Text.Trim());

            double n1, n2, n3, acum;

            n1   = Convert.ToDouble(TxtExamen1.Text);
            n2   = Convert.ToDouble(TxtExamen2.Text);
            n3   = Convert.ToDouble(TxtExamen3.Text);
            acum = Convert.ToDouble(TxtAcumulativo.Text);

            double prom = n1 + n2 + n3 + acum;

            if (prom >= 65)
            {
                LsbCondicion.Items.Add("APROBADO");
            }
            else
            {
                LsbCondicion.Items.Add("REPROBADO");
            }
        }
        private void FrmCalcular_Nota_Total_del_Estudiante_Load(object sender, EventArgs e)
        {
            double Acum, Exam;

            Acum = Convert.ToDouble(TxtAcumulativo.Text.Trim());
            Exam = Convert.ToDouble(TxtExamen.Text.Trim());


            Ntl.NotaExam(Acum, Exam);

            TxtAcumulativo.Clear();
            TxtExamen.Clear();
            TxtAcumulativo.Focus();
        }