Question

Evaluate :$\left\{\right(405{)}^2-\left(395{)}^2\right\}$

Answer 1

$\left\{\right(405{)}^2-\left(395{)}^2\right\}=(405+395)(405-395)\{a^2-b^2=(a+b\left)\right(a-b\left)\right\}=800\times 10=8000$