Regulate the version of a WordPress installation:
WordPress shows the version number at the end part (bottom) in admin interface.
New version of WordPress shows the version number in the ‘at a glance box’.
You will be able to determine the WordPress version by checking the version.php file
Follow the steps to check:
Navigate to the wp-includes directory in the directory where you installed WordPress. You can do this several ways:
command line using SSH.
cPanel using File Manager.
From an FTP client.