for http://microplugins.blogspot.com/2013/09/calc-20.html

      $(document).ready(function() {
        $('select.example1, input.example1').change(function() {
            console.log($(this).val());
            countExample1();
        });
        $('button.example1').click(function() {
            countExample1();
        });
        function countExample1() {
            var total = 0;
            $('select.example1').each(function() {
                total += parseFloat($(this).val());
            });
            if ($('input.example1').is(':checked')) total += 1;
            $('div.example1').html('Total: '+total);
        }
      });