If the sum and difference of two number are 20 and 8 respectively, then the difference of their squares is: 

The value of $${4- \sqrt{0.04} \over 4+\sqrt{0.4} } $$  is closed to

Assume that
$$\sqrt{3} = 3.605 \ (approximately)  $$
$$\sqrt{130} = 11.40 \ (approximately)  $$
Find the value of
$$\sqrt{1.3} + \sqrt{1300}+\sqrt{0.013}  $$

The smallest natural number, by which 3000 must be divided to make the quotient a perfect cube, is : 

The value of x in the given equation
$$ {23 ^2 + \sqrt{x}=625}$$

Simplify : $$\sqrt{[(12.1)^2-(8.1)^2]÷[(0.25)^2+(0.25)(19.95)]} $$

The value of $$ {\sqrt{0.6912}+{\sqrt{0.5292}}\over {\sqrt{0.6912}-{\sqrt{0.5292}}}}$$ is:

What mathematical operation should come at the place of ‘?’ in the equation:
2 ? 6 – 12 ÷ 4 +2 =11.