Question

Arrange the following in increasing order of their values from top to bottom.

• A. $13\times 4$
• B. $11\times 3$
• C. $12\times 5$
• D. $15\times 2$

Answer 1

$13\times 4=(6\times 4)+(7\times 4)$
$=24+28=52$

Similarly,
$15\times 2=(10\times 2)+(5\times 2)$
$=20+10=30$

$11\times 3=(10\times 3)+(1\times 3)$
$=30+3=33$

$12\times 5=(6\times 5)+(6\times 5)$
$=30+30=60$

So, $(15\times 2)<(11\times 3)<(13\times 4)<(12\times 5).$