Question

Express the following as difference of two squares: $505\times 495$;

Answer 1

As we know formula $a^2-b^2$ = $(a+b)(a-b)$
Also $505=500+5$ and $495=500-5$

Thus,
$505\times 495=(500+5)(500-5)$
$=(500{)}^2-(5{)}^2$
$=2500-25$
$=2475$