public Form1()
        {
            InitializeComponent();
            textBox2.KeyPress += new KeyPressEventHandler(textBox2_KeyPress);
            textBox3.KeyPress += new KeyPressEventHandler(textBox3_KeyPress);
        }
        void textBox2_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
                textBox3.Focus();
        }
        void textBox3_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
                calc();
        }
        void calc()
        {
            textBox5.Text = Math.Round(Convert.ToDecimal(Convert.ToDecimal(textBox2.Text) / Convert.ToDecimal(textBox3.Text)), 1) + " to 1";
            textBox1.Text = (Math.Round((Convert.ToDecimal(textBox3.Text) / (Convert.ToDecimal(textBox3.Text) + Convert.ToDecimal(textBox2.Text))) * 100, 1)).ToString() + "%";
        }
        private void button2_Click(object sender, EventArgs e)
        {
            calc();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox2.Text = textBox3.Text = textBox5.Text = "";
        }