public function getFractionalPart()
    {
        if (0 === $this->exponent || '0' === $this->coefficient) {
            return '0';
        }

        if ($this->exponent > strlen($this->coefficient)) {
            return str_pad($this->coefficient, $this->exponent, '0', STR_PAD_LEFT);
        }

        return substr($this->coefficient, -$this->exponent);
    }