<p>Enter First Number :</p>
<br>
<input type="text" id="Text1" name="TextBox1" oninput="add_number()">
<br> <p>Enter Second Number :</p>
<br>
<input type="text" id="Text2" name="TextBox2" oninput="add_number()">
<br>Result :
<br>
<input type="text" id="txtresult" name="TextBox3">