• We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
I forget with this game in particular, but it's usually in the main game menu, right next to the version number.

If you have the game in Steam, then it will be the latest version automatically.
 
Upper left when the game menu is up and you have the "start game" and "option" buttons. The correct checksum is CMLE.