function calCulate() {
  var thickness = document.calc.thickness.value;
  var area = document.calc.area.value;

   if (thickness == "") {
    alert("Material Thickness is required.");
    document.calc.thickness.focus();

   }

      if ( area != "") {
       document.calc.packs_reqd.value = Math.round(area / thickness) ;
   
	  }

//   if (pack_coverage >= area) {
  //    var packs_reqd = 1;
   //   document.calc.packs_reqd.value = packs_reqd;
  // }

  // if (area > pack_coverage) {

    //  var modulus_val = area % pack_coverage;

	//  if (modulus_val > 0) {
      //   new_area = area - modulus_val;
       //  packs_reqd = new_area/pack_coverage;
       //  packs_reqd = packs_reqd + 1;
        // document.calc.packs_reqd.value = packs_reqd;

     // } else {
       //  document.calc.packs_reqd.value = packs_reqd;
    //  }


  // }

   // field validity checking




   if (area == "") {
    alert("Floor Area in Square Meters is required.");
    document.calc.area.focus();

   }




} // end fn calCulate