The value of P 4 6 + 4 · P 3 6 is ______.

Formula for $$${}^{\mathrm{n}}\mathrm{P}_{\mathrm{r}}=\frac{\mathrm{n}!}{\left(\mathrm{n}-\mathrm{r}\right)!}$

${}^{6}P_4+4.{}^{6}P_3=\frac{6!}{2!}+4\times \frac{6!}{3!}$

                        $=\frac{6\times 5\times 4\times 3\times \bcancel{2\times 1}}{\bcancel{2\times 1}}+4\times \frac{6\times 5\times 4\times \bcancel{3\times 2\times 1}}{\bcancel{3\times 2\times 1}}$

$=360+4\times 120=360+480$

 $=840$