$ sudo apt-get update
$ sudo apt-get install console-keymaps-dec 

console-keymaps-dec is installed in your system.

Make ensure the console-keymaps-dec package were installed using the commands given below,

$ sudo dpkg-query -l | grep console-keymaps-dec *

You will get with console-keymaps-dec package name, version, architecture and description in a table

console-keymaps-dec package basic information: