function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
      if (charCode!=46 && charCode!=8 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }
function bl()
{
var l= document.form1.l.value;
var w= document.form1.w.value;
var h = document.form1.h.value;
if((l=="" && w=="" && h=="" )||(l=="" || w=="" || h=="" )) 
{
alert("please enter value for all fields");
}
else
{
var ww =l*w*h;
document.form1.ww.value = l*w*h;
var cc = (ww/231);
document.form1.cc.value=(ww/231);
}
}