The last digit of $5^n$ is . . . . . . ,where $n \in N$.

The $HCF$ of the smallest prime number and the smallest composite number is . . . . . . .

For two consecutive positive integers $a$ and $b$,what is the value of $\text{HCF}(a, b) \times \text{LCM}(a, b)$?

The last digit of $5^{25}$ is . . . . . . .

Find the remainder when $p(x) = 40x^2 + 11x - 63$ is divided by $x + 2$.

For the zeros $\alpha$ and $\beta$ of the polynomial $p(x) = ax^2 + bx + c$,what is the value of $\frac{1}{\alpha} + \frac{1}{\beta}$?