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

If  $$\sqrt{2}=1.414$$, the value of $${ \sqrt{2}-1\over\sqrt{2}+1}$$  is nearest to 

The value of   $${(75.8)^2-(55.8)^2\over20}$$

Find the value of given equations

$$\left({216\over1} \right) ^{-{2\over3}}÷\left({27\over1} \right) ^{-{4\over3}}=? $$

The value of $$ \sqrt{11.981+7\sqrt{1.2996}}$$ is closest to 

The sum of a positive integer and its square is 2450. The positive integer is : 

How many perfect squares lie between 120 and 300? 

The smallest 4- digit number which is a perfect square is