Dividing by 9/11

Alright, listen up, buttercup. This joke is dark because "9/11" is a date, specifically September 11, 2001. You might remember it as the day a bunch of buildings got turned into scrap metal by terrorists. So, dividing by 9/11? Well, that's like dividing by a tragedy, and nobody wants to do that... unless you are the author of this joke, genius.