The correct expression of $5 . \overline{45}$ in the fractional form is

$1+1 \div\left\{1+1 \div\left(1-\frac{1}{3}\right)\right\}=?$

What is the simplified value of $(3+1)(3^{2}+1)(3^{4}+1)(3^{8}+1)(3^{16}+1)?$

What value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)
$21 + 39 \times 2.9 + 8.99 = ?$

$13 \frac{4}{?} + 5 \frac{3}{4} \text{ of } 3 \frac{1}{5} \div 4 \frac{3}{5} = 17 \frac{4}{5}$

If $x + (1/x) = 2$,then what is the value of $x^{21} + (1/x^{1331})$?