Nine is one of the numbers at the equation playground. He always acts all radical and cool, and is attached to his skateboard/sunglasses. He can be very sensitive at times, and loses his cool without his skateboard/sunnies. He has a pet cat that he also gave sunglasses to. The things he does in his spare time include playing games with the other algebraliens, skateboarding, and hanging out with his best friend, Six (who he's actually in love with). He can honestly be pretty idiotic.