code: public String getNumberText(final int digits) {
      String result = "";
      for (int i = 0; i < digits; i++) {
        result = result + random.nextInt(10);
      }
      return result;
    }
docs: Returns a string containing a set of numbers with a fixed number of digits
  
  @param digits number of digits in the final number
  @return Random number as a string with a fixed length