There are a lot of industries where the number of the week in a year is as significant as the day of the week. Up until now, Google Calendar's desktop site hasn't actually shown that information natively, which was a bummer for those that might have needed it. But, that particular omission has now been remedied, as Google has added a setting to show week numbers on the desktop site for Google Calendar.
The new option in Settings (left), numbered weeks in month view (right).
The new option is in Settings (open the cog icon at the top left, select "Settings") -> View options -> Show week numbers. Previously to get week numbers to appear you had to use a workaround like importing a custom calendar, and even then it didn't look quite so nice as this new setting.
Week number has been available on the Google Calendar app for Android for a bit now, so it's nice to see the desktop site getting the same feature.
Thanks: Nicolai von Hirsch