Math Problem For Today

Calculate the number of hours I slept during my migraine on Tuesday.
Divide by the number of comments I got on this post.

(If this results in a "divide by zero" error, I apologize in advance for the universe exploding and the world ending.)

Add four.

Subtract the number of times per week I shake my head in confusion while admitting to myself that I still really have no clue who "Justin Bieber" is.
(Extra credit if you deduce whether or not I actually care.)
.