how to display data on textbox when event is clicked?

i have create web app
in which taken three textboxes
when i entered value in textbox1..i want that value should display on textbox2 and textbox3


code is behind

public class Class1
{


          public double cal(double amount)
        {
            return((amount+(amount*0.01)));
        }










}

 protected void TextBox1_TextChanged(object sender, EventArgs e)
    {

        Class1 c = new Class1();
        TextBox2.Text = c.cal(Convert.ToDouble(TextBox1.Text)).ToString();
 TextBox3.Text = c.cal(Convert.ToDouble(TextBox1.Text)).ToString();
    }




 protected void Button1_Click(object sender, EventArgs e)
    {
        Class1 c = new Class1();
        TextBox2.Text = c.cal(Convert.ToDouble(TextBox1.Text)).ToString();
    }

on button_click its working but not on textbox_textchanged

so telll me on this regard

Tags: C# (C# 4.0), .NET (.NET4), ASP.NET