Twilight Sparkle goes on another rampage when Cutie Mark Crusaders ask her a mathematical riddle she can't solve. As usual, it's up to her friends to try to stop her before her magic frenzy causes serious damage.

But... among her friends, is there anypony more skilled at math who could hope to solve a riddle even Twilight has trouble with?

Brotip: try to help Twilight with the riddle yourself as you read. :D