What is the square root of 0.09 ?

Direction : What should come in place of the question (?) in the following question.

(?)² + (65)²=(160)² -  (90)² – 7191

Find the value of given expression.

30 – [40 – {56 – (25 – 13 – 12)}]

The smallest positive integer when multiplied by 392, the product is a perfect square, is 

23+ 3+33+333+3.33=?

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

$$ {1\over 8}×(223+?)=71$$

The number, whose square is equal to the difference between the squares of 975 and 585, is: 

$$ {\sqrt{784}} × \sqrt{6.25} + 56\%\ of\ 450=?+186$$