Question

Evaluate the following (using identities):

$103\times 105$

Answer 1

Given, $\left(103\right)\left(105\right)$

$\Rightarrow (104-1)(104+1)$.

We know, $a^2-b^2=(a+b)(a-b)$.

Then,

$\left(103\right)\left(105\right)$

$=(104-1)(104+1)$
$=(104{)}^2-1^2$
$=10816-1$
$=10815$.

Therefore, the required answer is $10815$.