Quick: What's halfway between 1 and 9? According to a recent study, most little kids will answer "3," as will many people in non-literate cultures. And as it turns out, there's a solid evolutionary reason why that guess makes sense.
It would have been easy to get the math right in Touch. On the other hand, taken literally, the portrayal of the application of mathematics to the world by the young Jake is so way-over-the-top fictitious that inaccuracy in specific details does not adversely affect the storyline.