PostalCost

        private void button1_Click(object sender, EventArgs e)
        {
            double PostalCost;
            PostalCost = CalculateCost(Convert.ToInt32(textBox1.Text));
            if (PostalCost > 0)
                textBox2.Text = PostalCost.ToString();
            else
                textBox2.Text = "To heavy";
        }

        private double CalculateCost(int Weight)
        {

            if (Weight > 0 && Weight <= 8)
                return 0.32;
            else if (Weight > 8 && Weight <= 12)
                return 0.47;
            else if (Weight > 12 && Weight <= 16)
                return 0.62;
            else if (Weight > 16 && Weight <= 20)
                return 0.77;
            else if (Weight > 20 && Weight <= 24)
                return 0.92;

        return 0.0;

        }
    }