The product of $HCF(a, b)$ and $LCM(a, b)$ is equal to:

Using Euclid's division algorithm,find the Highest Common Factor $(HCF)$ of the following pair of numbers and determine if they are co-prime:
$847, 2160$

The length,breadth,and height of a prayer room are $15\,m$,$12\,m$,and $21\,m$ respectively. Determine the longest rod which can measure the three dimensions of the room exactly. (in $,m$)

Find the $g.c.d.$ of $240$ and $6552$ using Euclid's division algorithm.

If $p$ and $q$ are distinct prime integers,then their Least Common Multiple $(LCM)$ will be ...........

$A$ sweetseller has $420$ kaju barfis and $130$ badam barfis. She wants to stack them in such a way that each stack has the same number,and they take up the least area of the tray. What is the number of barfis that can be placed in each stack for this purpose?