Question

Match the following products with their respective values.

• A. $100$
• B. $45$
• C. $147$

Answer 1

$\bullet 4\times 25$ can be written as $4\times (20+5)$. This multiplication can be solved using box method as:

	$20$	$5$
$4$	$20\times 4$ $=10\times 2\times 4$ $=10\times 8$ $=80$	$5\times 4=20$

Hence,
$4\times 25$
$=4\times (20+5)$
$=80+20$
$=100$

$\bullet 3\times 15$ can be written as $3\times (10+5)$. This multiplication can be solved using box method as:

	$10$	$5$
$3$	$10\times 3=30$	$5\times 3=15$

Hence,
$3\times 15$
$=3\times (10+5)$
$=30+15$
$=45$

$\bullet 7\times 21$ can be written as $7\times (20+1)$. This multiplication can be solved using box method as:

	$20$	$1$
$7$	$20\times 7$ $=10\times 2\times 7$ $=10\times 14$ $=140$	$1\times 7=7$

Hence,
$7\times 21$
$=7\times (20+1)$
$=140+7$
$=147$