Hi,
I have created sample.based on TextChanged Event of TextBox.
HTML
<div>
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td>
Enter First Number :
</td>
<td>
<asp:TextBox ID="txtNumber1" runat="server" OnTextChanged="Calculate" AutoPostBack="true" />
</td>
</tr>
<tr>
<td>
Enter Second Number :
</td>
<td>
<asp:TextBox ID="txtNumber2" runat="server" OnTextChanged="Calculate" AutoPostBack="true" />
</td>
</tr>
<tr>
<td colspan="2">
<asp:Label ID="lblResult" runat="server" />
</td>
</tr>
</table>
</div>
Code
protected void Calculate(object sender, EventArgs e)
{
decimal num1 = !string.IsNullOrEmpty(txtNumber1.Text) ? decimal.Parse(txtNumber1.Text) : 0;
decimal num2 = !string.IsNullOrEmpty(txtNumber2.Text) ? decimal.Parse(txtNumber2.Text) : 0;
lblResult.Text = (num1 * num2).ToString("N2", CultureInfo.CreateSpecificCulture("hi-IN"));
}
Screenshot
