31 March 2016 - 7 times 13

traveler: Hi!
Hugh Everett: What the which?!? Where’d you come from?
traveler: I’m a dimension traveler from another universe. Hey, this place looks a lot like home.
Hugh Everett: Sure, sure.
traveler: Let me run a scan.... Oh, there’s the difference. What are the factors of 91?
Hugh Everett: Uh, seven times thirteen.
traveler: In my universe 91 is prime. That’s the only difference.
Hugh Everett: So you’re here to make fun of my worldsview?
traveler: In a way, maybe. At least it explains why you were surprised to see a dimension traveler.
Hugh Everett: Yeah?
traveler: How could you work out the theory when math is so messed up?