$$ { \sqrt{(0.798)^2+0.404×0.798+(0.202)^2}+1=?} $$

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

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

$$ {4\over 7}×{2{4\over 5}÷{2\over 5}=?}$$

The sum of the squares of 2 number is 146 and the square root of one of them is 5. The cube of the other number is 

Simplify : $$ {(2x)^{2}-(2y)^{2}-(4x)^{2}}$$

By what least number should 4320 be multiplied so as to obtain a number which is perfect cube? 

Direction: What approximate value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)

(31.99)^1/5 × (80.78)^1/4 × (5.15)² = ? × 2.29

$$ \sqrt{0.00004761} $$   equal to