To tell which Windows version you have, there are several simple methods:

1. Use the keyboard shortcut Windows key + Pause/Break key to open a System Information window showing your Windows edition and system details.
2. Press Windows key + R to open the Run dialog, type "winver" and press Enter. This opens a window showing your Windows version and build number.
3. Open the Settings app by clicking Start > Settings (or pressing Windows key + I). Then go to System > About. Under "Windows specifications," you will see your Windows edition, version, and OS build.
4. Open Command Prompt (Windows key + R, then type "cmd" and press Enter), then type "systeminfo" and press Enter. This command lists comprehensive system details including Windows version and build.

These methods work for different Windows versions such as Windows 10 and Windows 11, and will give you precise information about your currently installed Windows version and build number.