Easy way to convert Chrome and Opera browser versions

Opera switched from their own Presto engine on Opera 12 to using the Chromium/Blink engine for Opera 15+.

The easy way to convert the Opera version to the Chromium engine version is to just add/subtract 13.

Using this technique, you can quickly figure out that Opera 15 uses Chrome 28 and any new web-tech features on Chrome 60 will be available on Opera 47.