public function times($factor)
    {
        if ($factor < 0) {
            $this->invert = $this->invert ? 0 : 1;
            $factor = -$factor;
        }

        $this->years = (int) round($this->years * $factor);
        $this->months = (int) round($this->months * $factor);
        $this->dayz = (int) round($this->dayz * $factor);
        $this->hours = (int) round($this->hours * $factor);
        $this->minutes = (int) round($this->minutes * $factor);
        $this->seconds = (int) round($this->seconds * $factor);
        $this->microseconds = (int) round($this->microseconds * $factor);

        return $this;
    }