Question

Evaluate $33\times 27$ using suitable identity.

Answer 1

Using Formula $(x+a)(x+b)$ = $x^2+(a+b)x+ab$

Writing $33$ as $30+3$ and $27$ as $30-3$

So, $33\times 27$

$=(30+3)(30-3)$

$={30}^2+[3+(-3\left)\right]30+\left(3\right)(-3)$

$=$ $900+\left[\right(0\left)30\right]-9$

$=$ $891$

Hence, $33\times 27=891$