Question

Using standard identity, solve:
1010×990 = .

• A. $999900$
• B. $100000$
• C. $990000$
• D. $119900$

Answer 1

The correct option is A $999900$

$1010$ and $990$ can be written as $(1000+10)$
and $(1000-10)$ respectively.

$1010\times 990=(1000+10)(1000-10$
$[\text{We know,}{a}^2-b^2=(a+b\left)\right(a-b\left)\right]$
$={1000}^2-{10}^2$
$=1000000-100$
$=999900$