// determines whether the value is numerical
function IsNumeric(sText)

{
   var ValidChars = "0123456789.";
   var IsNumber=true;
   var Char;

 
   for (i = 0; i < sText.length && IsNumber == true; i++) 
      { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) 
         {
         IsNumber = false;
         }
      }
   return IsNumber;
   
};
// 
$(function(){

    $('.qty_input').blur(function(){
    
        var $this = $(this);
    
        var orderNumber = $this.val();
        var price = $this
                            .parent().parent()
                            .find("td.price span")
                            .text();
        
        if ( (IsNumeric(orderNumber)) && (orderNumber != '') ) {
            
            var total = orderNumber * price;
			var total = total.toFixed(2);
            
            $this
                .parent().parent()
                .find("td.tot input")
                .val(total);                    
            
        };
    });

});