Players answering a Quick Maths question.
Quick Maths
From the Hypixel Pit Wiki

Quick Maths is a minor event that occasionally occurs in The Pit. When the event starts, a randomly-generated math equation will appear in the chat. The first five players to answer it correctly will receive 250 XP and 500 gold. The equations are intended to be easy and solvable without a calculator, typically involving one- or two-digit addition and multiplication. Most Quick Maths events are over in under five seconds.