Chechbox sudetis

<div class="budai">
    <input type="checkbox" id="group1_1" value="1" /> as <br />
    <input type="checkbox" id="group1_2" value="2" /> ab <br />
    <input type="checkbox" id="group1_3" value="3" /> nm <br />
    <input type="checkbox" id="group1_4" value="4" /> jj <br />
</div>
<div id="pkaina"></div>
///
$(function() {
    var kaina = 0;
    $('.budai :checkbox').click(function() {
         if ($(this).is(':checked')) {
            kaina += Number($(this).val());
         }else{
            kaina -= Number($(this).val());
         }
        $('#pkaina').text(kaina);
    });
});