Quick Math: 100m+ Birthday Actions on Facebook per Day?

A rather obvious finding from my birthday yesterday: Facebook is immensely popular. My Facebook wall, email, notifications and SMS alerts were bombarded with birthday notes... several magnitudes greater than last year... and similarly the year before.

To be clear: this says a great deal about Facebook (popular!) and nothing about me (not popular!). Facebook usage and engagement are unbelievably high: at F8, Alex Schultz said that half of Facebook's 400m active users were active *each* day. And judging by the steady stream of comments and messages, users are doing more than logging in: they are viewing the birthday alerts, actively reading the feeds, giving Facebook gifts, creating JibJab cards, etc. It would be fun - and overwhelming - to look at the total number of Facebook actions / engagements that happen around birthdays each day. If you apply basic math and use me as an example:

- ~400m Facebook users - ~1.1m birthdays / day - ~100 actions per birthday

... Thats something in the range of 100m+ birthday actions a day. My guess is that last year's numbers were 10% of this.