How do I find out which version (number) of the pack is installed.

It has been a while since I installed the pack so I only now know that it isn't the newest, but for the love of god I don't remember when I downloaded it / installed it.
And therefore I can't figure out the version. A incompatibility with some other software has creeped up and I think it is better they know which version has caused the problem, so that they can sort their end better out.

Edit: just found out I installed it on 30th October of 2016 so it must be before K-Lite Codec Pack 12.6.5

So how do I exactly find out which version number I have installed?

nvm I found the old installer named 1244 so I guess it was 12.4.4

The Codec Tweak Tool displays the installed version in its title bar.
You can also view the version in the programs list in the Windows Control Panel, where you can uninstall software.