Алексей

$(function () {
  $('#id_rooms').bind('blur keyup change', function () {
    var n = $('#id_rooms').val() || 0;
    $("input#id_form-TOTAL_FORMS]").attr('value', n);
    $(".extrafieldWrapper").empty();
    for (var i = 0; i < n; i++) {
      $(".extrafieldWrapper").append("<br/><label for='id_form-" + i + "-adult'>Adult:</label> <input id='id_form-" + i + "-adult' type='number' name='form-" + i + "-adult'/> <label for='id_form-" + i + "-children'>Children:</label> <input id='id_form-" + i + "-children' type='number'  name='form-" + i + "-children'/>");
    }
  });
});