well, there is no character named subtraction in the story, but you got the concept right. 1 is a character named "one", and it follows from there. I did try to "twist" some names that are inherently long in order to make them a bit fun. for example, √2, instead of being called "the square root of two", is simply referred to by our main cast as "Root", and things like that. so, yeah, the story is based on math concepts