Question

Find the value of the product $(-6)\times (-7).$

• A. $-42$
• B. $42$
• C. $36$
• D. $-49$

Answer 1

The correct option is B $42$

$\underset{–}{\text{Need to find:}}$ Value of $(-6)\times (-7)$

$(-6)\times (-7)$ can be written as

$(-6)\times (-7)=(-1)\times 6\times (-1)\times 7$
$=(-1\times -1)\times (6\times 7)$

As we know that $-1\times -1=1$, then

$(-6)\times (-7)=1\times 6\times 7=6\times 7$

$6\times 7$, i.e., multiplying $6$ by $7$ denotes $7$ times addition of $6$ or $6$ times addition of $7$.

Now, $6$ when added $7$ times would give the value as:

$\underset{–}{6+6}+\underset{–}{6+6}+\underset{–}{6+6}+6$
$=12+12+12+6$
$=\underset{–}{12+12}+\underset{–}{12+6}$
$=24+18$
$=\underset{–}{24+18}$
$=42$

$\therefore (-6)\times (-7)=6\times 7=42$

Hence, the value of the product $(-6)\times (-7)$ is $42,$ i.e., option (b.) is the correct one.