title: jQuery Sum show NaN
body: <p>On keyup on price, I am calculating the total price of (quantity * unit price) individual products and at the end I have field which will auto generate the grand total of all individual totals. I was able to auto calculate the individual totals but I am stuck on the grand total. It shows NaN. How can I fix it ?</p>
  
  <p>code:</p>
  
  <pre><code>$('.prc').on('keydown keyup', function(){
      // total_array = [];
      flag = $(this).attr('flag');
      prc = $(this).val();
      qntty = $('.qntty_'+flag).val();
      mul = prc * qntty;
  
      total = 0;
  
      total = total + parseFloat($('.total_'+flag).val(mul));
  
      $('#total').val(total);
  
  })
  </code></pre>