The HCF and the LCM of two numbers are $30,420$ respectively. If one of the numbers is $60$, then find the other number.

Find the other number:

As we know$HCF\times LCM=Productofthetwogivennumbers$

Let be the $K$ other number.
$\begin{array}{rcl}30\times 420& =& 60\times K\\ K& =& 210\end{array}$

Hence, $210$ is the other number.