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

Prove that $7\sqrt{5}$ is an irrational number.

If $m$ and $n$ are distinct prime integers,then their $HCF$ is .......... .

If $HCF(a, b) = 1$,then $HCF(a - b, a + b)$ is equal to:

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

$3 + \sqrt{16}$ is a . . . . . . number. (Rational,Irrational,Negative integer)