He is voiced by Jack McBrayer.
He first met Wordgirl when she was battling Doctor Two-Brains.
He has dark brown hair that stands straight up and a square face. He wears glasses in and out of costume. He is shorter than most kids in the fifth grade.
As Kid Math, he wears a bright cyan outfit with white gloves and boots, a yellow utility belt, and a symbol on his chest: a cyan equals sign on a white circle.
As Rex, he wears a red hoodie, teal shorts and.sneakers. His Kid Math costume is visible underneath.
He thinks things through logically, possibly due to his Hexagonian origins. He is new to being a superhero, and messes up sometimes, though he is eager to get better.
- Extremely good at math (can calculate probabilities and equations in seconds)
- He is one of the only characters to figure out Wordgirl's secret identity, the others being Tobey (temporarily), Dr. Two Brains (also temporarily), Scoops, Violet and Bampy. Part 2 of the episode that's about him show that he has a crush on Violet.