In the scene where Jeff Goldblum is showing the President how much time is left until the aliens attack (0:43:46), watch as Jeff turns his laptop towards the screen. The "time left" is shown as follows:

00:28:00:08

00:28:00:05

***00:28:00:07***

***00:28:00:56***

Later in the scene...

00:27:59:28

00:27:59:13

***00:27:59:18***

***00:27:59:05***

***00:27:59:07***

***00:27:59:01***

***00:27:59:56***

And again...

00:27:58:44

***00:27:58:49***

***00:27:58:34***

and continuing in this pattern!