What is the least number that can be added to the number $1020$ to make it a perfect square?

What is the least number which should be subtracted from $0.000326$ to make it a perfect square?

$\sqrt{\frac{0.256 \times 0.081 \times 4.356}{1.5625 \times 0.0121 \times 129.6 \times 64}} = ?$

$\sqrt{176+\sqrt{2401}} = ?$

In the following questions,two equations numbered $I$ and $II$ are given. You have to solve both the equations and give the answer.
$I: \frac{13}{\sqrt{x}} + \frac{9}{\sqrt{x}} = \sqrt{x}$
$II: y^4 - \frac{(13 \times 2)^{9/2}}{\sqrt{y}} = 0$

$\sqrt{33124} \times \sqrt{2601} - (83)^{2} = (?)^{2} + (37)^{2}$