Verifying Magento version

To check/verify Magento version of your Magento installation you can login into Magento backend ( http://your-store-name/admin/ ) and scroll down to the footer. Current Magento version should be shown there:

If due to some reason you do not have Magento version shown in the footer it can be checked in Magento Connect Manager:

• switch to Magento Connect Manager at System > Magento Connect > Magento Connect Manager or by pointing your browser to http://your-store-name/downloader/
  
• check version of Mage_All_Latest package:
  

As a last resort, Magento version can be checked in app/Mage.php file of your Magento installation, simply search for getVersionInfo() function there:

    public static function  
    {
        return array(
            'major'     => '1',
            'minor'     => '6',
            'revision'  => '1',
            'patch'     => '0',
            'stability' => '',
            'number'    => '',
        );
    }