formula float point problem

[Marvin He]

Hi all,
   I use this code
     CellValue cellValue = formulaEvaluator.evaluate(cell);
     cellValue.getNumberValue();
  to evaluate formula in xls.   (POI version is 3.9)
[http://mail.163.com/js6/s?func=mbox:getMessageData&sid=rASZXZvcSBXKmRJLyyccScGTxNPHKMLm&mid=88:1tbiWB-bPluHkST5CAABs7&part=3][cid:image002.png@01D4613F.52525B70]
  and display value is 21.1, but parsed value is 21.099999999999998.
  Can I get the same value with the display one ?  (I know POI get the 'cached' 
value in xml, but excel display the different value based on the xml)
  Also I want to scale 2 point . but the value will add two o. For example:  3  
-> 3.00

please give me some advice.

Best regards，
marvin