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<SCRIPT TYPE="TEXT/JAVASCRIPT">
//<![CDATA[
 Number.prototype.toFixedOf = function (n){
  if(!n || typeof n != "number" || n > 12) return NaN;
  var reck = 1;
  for (var i=0; i<n; i++) reck *= 10;
  return parseInt(this * reck)/reck;
 }
  
 var num = 3223.987654321234567890123456789
 alert( num.toFixedOf(5) );
//]]>
</SCRIPT>