If a + b + c = 12, a² + b² + c² = 52, then what is ab + bc + ca equal to-

Simplification the following equations shown below

What approximate value should come at place of the question mark(?) in the following question?

Direction : What value should come in the place of question mark (?) in the following questions?

125% of 2440 – 75% of 1856 = ?

Simplify the following equation.
$$ {(100)}^{1\over2}.{(0.001)}^{1\over3}-{(0.0016)}^{1\over4}.{3}^{0}+({5\over4})^{-1} $$

The largest number of five digits, which is a perfect square is 

If a² + a + 1 = 0 then the value of a⁹ is.