Simplify $\left(5+\sqrt{7}\right)\left(2+\sqrt{5}\right)$.

Consider the following statements:

(i) For every positive real number $x,x-10$ is positive.

(ii) Let $n$ be a natural number. If $n^2$ is even, then $n$ is even. $f$

(iii) If a natural number is odd, then its square is also odd.

Then

Rationalise the denominator and simplify :

$\frac{\sqrt{5}+\sqrt{3}}{\sqrt{5}-\sqrt{3}}$

When the digits within the number are multiplied with each other, the product of which of the following numbers is the lowest?

$435,224,823,902$

Which among the following is not an irrational number?