Direction: what should come in place at question mark(?).

$$ {\sqrt{4489}+(71)^{2}-(?)^{2}=2707}$$

If $${a+b=10}$$ and $$ \sqrt{a\over b}-13=-\sqrt{b\over a}-11$$, then what is the value of $${3ab+4a^2+5b^2}$$?

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

What is the value of $$ {0.55 × 4.5\over 0.81}$$ ?

On simplification of   $$ {(2.664)^2-(2.356)^2\over0.288}$$

The smallest number that must be subtracted from 1000 to make the resulting number a perfect square is 

Evaluate: $${-(4-6)^2-3(-2)+।-6।\over 18-9÷3×5}$$

  $$25\% \ of (50\% \ of \ 30\% \ of \ 150)\over 40\% of \ 2250$$ is equal to: