You need to use Js
onFocus
Event.
Suppose there are three textbox named,
TextBox1,TextBox2,TextBox3
Then write onFocus Event on TextBox3 Like.
<asp:textbox id="TextBox3" runat="Server" onfocus="javascript:focused(this)" xmlns:asp="#unknown" />
function focused(txt3)
{
var result = document.getElementById("TextBox1").value * document.getElementById("TextBox2").value;
txt3.value = result;
}
[Additional answer]
You could use
THIS[
^]
[/additional answer] to count date difference.
and your'e done.
Please
vote and
Accept Answer if it Helped.