public static String addToNumberString(String numberString,long addAmount){
  if (numberString == null)   return null;
  int origLength=numberString.length();
  long number=Long.parseLong(numberString);
  return padNumberString(Long.toString(number + addAmount),origLength);
}

public static String addToNumberString ( String numberString , long addAmount ) { if ( numberString == null ) return null ; int origLength = numberString . length ( ) ; long number = Long . parseLong ( numberString ) ; return padNumberString ( Long . toString ( number + addAmount ) , origLength ) ; }
add the number to the string , keeping ( padding to min of original length )
