Pi (π) is an algebralian character who made their first appearance in "The Number Playground Chronicle!" and appears as the main antagonist in "Pie Vs Pi: The Pi Day Massacre". They reported on if the Equation Playground was OK or not in Section B, with the verdict being "OK"; and reported on the admission rates and prices for it. They are also credited for the photo of Five on the cover of Section A after he dropped the ball playing catch with Three, as seen in "X Finds Out His Value".