$ sudo apt-get update
$ sudo apt-get install cernlib-montecarlo 

cernlib-montecarlo is installed in your system.

Make ensure the cernlib-montecarlo package were installed using the commands given below,

$ sudo dpkg-query -l | grep cernlib-montecarlo *

You will get with cernlib-montecarlo package name, version, architecture and description in a table

cernlib-montecarlo package basic information: