The Algebastard refuses to hand it over unless Rick solves a "simple" equation: —a mathematical proof for the perfect hypothetical escape plan. Specifically: given infinite universes, calculate the exact probability of surviving a jump into a vat of acid while bad guys shoot at you, but only if the acid turns out to be fake, the floor is a trapdoor, and also you look cool doing it.
"Morty! Drop the ceiling-gunk, we’re going to the Exo-Math Dimension! It’s a whole reality where mathematical constants have physical form. I need to harvest the square root of a negative pineapple." rick and morty s06e03 tv
"You’ve been sitting incorrectly your entire life, Jerry. Slouching is a cry for help." The Algebastard refuses to hand it over unless
"The Vat of Acid Equation"
Morty solves the episode not by doing math, but by realizing the real vat of acid was the friends they made along the way—then immediately throwing Septimus into a logic bomb that deletes The Algebastard. Rick grabs the Irrational Residue, grumbling. Drop the ceiling-gunk, we’re going to the Exo-Math
"Oh jeez, Rick, can’t it wait? I promised Jessica I’d help her… I don’t know, exist near her at the mall food court."