Question

The solution of the following by using suitable identities:
$83\times 77$ is -------

Answer 1

The given product $83\times 77$ can be rewritten as $(80+3)\times (80-3)$ and we solve it as follows:

$(80+3)(80-3)=(80{)}^2-(3{)}^2(\because a^2-b^2=(a+b\left)\right(a-b\left)\right)=6400-9=6391$

Hence, $83\times 77=6391$.