}
      do {
        for (int j = 0; j < 2; j++) {
          intsToAdd[i][j] = randomBigInteger(Integer.SIZE - 2).intValue();
        }
      } while (!Impl.GUAVA.noAddOverflow(intsToAdd[i][0], intsToAdd[i][1]));
      do {
        for (int j = 0; j < 2; j++) {
          longsToAdd[i][j] = randomBigInteger(Long.SIZE - 2).longValue();
        }

  }

  /**
   * Chooses a number in (-2^numBits, 2^numBits) at random, with density concentrated in numbers of
   * lower magnitude.
   */
  static BigInteger randomBigInteger(int numBits) {
    while (true) {
      if (RANDOM_SOURCE.nextBoolean()) {
        return randomNonNegativeBigInteger(numBits);
      }
      BigInteger neg = randomNonNegativeBigInteger(numBits).negate();