private void printNumber(StringBuffer out,BigInteger number,int nDigits){
  String s=number.toString();
  for (int i=s.length(); i < nDigits; i++) {
    out.append('0');
  }
  out.append(s);
}

private void printNumber ( StringBuffer out , BigInteger number , int nDigits ) { String s = number . toString ( ) ; for ( int i = s . length ( ) ; i < nDigits ; i ++ ) { out . append ( '0' ) ; } out . append ( s ) ; }
prints an biginteger as a string .
