Edit in JSFiddle

 $(function() {
   $("input[name='chkPinNo']").click(function() {
     if ($("#chkYes").is(":checked")) {
       $("#dvPinNo").show();
     } else {
       $("#dvPinNo").hide();
     }
   });
 });

<div>Do you have Pin No?</div>
<label for="chkYes">
  <input type="radio" id="chkYes" name="chkPinNo" /> Yes
</label>
<label for="chkNo">
  <input type="radio" id="chkNo" name="chkPinNo" /> No
</label>
<hr>
<div id="dvPinNo" style="display: none">
  Pin No:
  <input type="text" id="txtPinNo" />
</div>

hr {
  display: block;
  margin-top: 0.5em;
  margin-bottom: 0.5em;
  margin-left: auto;
  margin-right: auto;
  border-style: inset;
  border-width: 1px;
}