Question

The value of $5\times 6\times 7\times 8$ is .

• A. $1680$
• B. $1630$
• C. $1650$

Answer 1

The correct option is A $1680$

To find out $5\times 6\times 7\times 8$, we first multiply $5$ and $6$.
Hence,
$5\times 6\times 7\times 8$
$=(5\times 6)\times 7\times 8$
$=30\times 7\times 8$

Next, we multiply $30$ and $7$.
Hence,
$30\times 7\times 8$
$=(30\times 7)\times 8$
$=(10\times 3\times 7)\times 8$
$=(10\times 21)\times 8$
$=\left(210\right)\times 8$
$=(200+10)\times 8$

Now, we use box method to find $(200+10)\times 8$.

	$8$
$200$	$200\times 8$ $=2\times 100\times 8$ $=100\times 2\times 8$ $=100\times 16$ $=1600$
$10$	$10\times 8$ $=80$

$\therefore (200+10)\times 8=1600+80=1680$

Hence, the value of $5\times 6\times 7\times 8$ is $1680$.