Question

Find the least number which must be added to $8902$ so that the sum becomes a perfect square.

Answer 1

$0$	$9$
$9$ $+9$	$\overline{89}\overline{02}$ $81$
$18$	$802$

Now,
$185\times 5=925$
Also,
$925-802=123$
$\therefore 123$ must be added to $8902$ to make it a perfect square.