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

If $p$ and $q$ are distinct prime integers,then their least common multiple $(LCM)$ is . . . . . . .

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

The $HCF$ of $13$,$23$,and $31$ is . . . . . . .

The decimal representation of $\frac{7}{2^3 \cdot 5^4}$ will have how many digits after the decimal point?

Find the $HCF$ and $LCM$ of the following pairs of integers and verify that $HCF \times LCM = \text{product of the two numbers}: 26$ and $91$.