docs: public static String truncate(int n, int smallestDigit, int biggestDigit) {
      int numDigits = biggestDigit - smallestDigit + 1;
      char[] result = new char[numDigits];
      for (int j = 1; j < smallestDigit; j++) {
        n = n / 10;
      }
      for (int j = numDigits - 1; j >= 0; j--) {
        result[j] = Character.forDigit(n % 10, 10);
        n = n / 10;
      }
      return new String(result);
    }