How to find version of Drupal installed

Question

How can I know which version of Drupal is installed in my server?

Answer 1

In Drupal 7

Open CHANGELOG.txt and the top most version will be the installed version.

In Drupal 8

Open core/lib/Drupal.php file and there will be a version mentioned like const VERSION = '8.1.8';

Drush Tool

Drush status

Admin Interface

Go to Administer -> Reports -> Status Report or enter URL /admin/reports/status

Above is the simplest way otherwise installed wappalyzer browser addons and see the magic.