checkNotNull(mode);
    if (q == 0) {
      throw new ArithmeticException("/ by zero"); // for GWT
    }
    int div = p / q;
    int rem = p - q * div; // equal to p % q

    if (rem == 0) {
      return div;
    }

    /*
     * Normal Java division rounds towards 0, consistently with RoundingMode.DOWN. We just have to