Saudi Arabia adopts the Gregorian calendar
If you&#x27;re on a Linux&#x2F;MacOS&#x2F;BSD machine, &quot;ncal -p&quot; on the command line gives you a nifty list of when various countries switched to Gregorian.<p>Interesting factoid: Russia&#x27;s &quot;October Revolution&quot; actually took place in November in most of the rest of the world!<p>(edit: I had originally said ncal works on all &quot;POSIX&quot; systems but that turned out to be incorrect)