Everyone loves brain teasers, but especially deceptively simple ones (deceptively-full-of-calculus problems aren't very fun) that are so intuitive, first graders often outperform adults—but what about ones mathematicians can't solve? The "3X+1 Problem," aka the "Collatz Conjecture," drives mathematician so bonkers it once was thought to be a Soviet plot to distract scientists from their work.

Anyone with a solid grasp of addition, division, multiplication can try it and anyone can see it in action—but no one can explain it, prove it, or disprove it. Tipping Point Math demonstrates it in this video, "The Simplest Impossible Problem," but a written explanation will be attempted below.