Luigi

Luigi is calculator savant with autism spectrum disorder and the younger brother of Mario. Along with Mario, Luigi worked for a circus, where he was a sideshow attraction dubbed "the human calculator". He is very skilled at performing rapid mental arithmetic and loves reciting sequences of numbers that he finds pleasing. Ever since the pair of brothers left the employ of the circus, he has lived with Mario. Luigi is relatively quiet and spends a lot of time playing with balloons in what he calls his "Balloon World" (a large pile of balloons in his bedroom).

Interesting Facts
Luigi has an affinity for cube numbers, which, along with balloons, is an interest he shares with his friend Christopher Boone. The two have been seen sharing lists of numbers and discussing balloons at great length.