The movie presents Raymond's talents with counting and calculation as falling into the (erroneous) statement of "stuff people with autism can do"—but it stands for so much more, really.

The fact that Raymond has a talent seems to spark Charlie's general realization that Ray is a human being, with awesome qualities as well as faults. Sure, the film attributes the talent to Raymond's autism… but nonetheless, it's an important moment in that Raymond's super duper math skills show Charlie that Ray comes with more than liabilities, which opens him up to seeing Raymond as more of a brother than a bargaining chip.

It's also worth noting that Charlie—the failed car salesman—is shown as being absolutely not good at numbers. You don't rack up debt if you're a savvy salesman, and this is compounded by the fact that Charlie's business failure is because he didn't have the math skills to understand emissions regulations. Sure, there was a bit of bad luck in there as well, but the emphasis on Raymond's mathematical genius underlines the fact that Charlie lacks the talent Raymond has.

In terms of big-picture symbolism, we can also read this as a little snarky commentary on the life of the American yuppie. Charlie—a yuppie personified—should be good at numbers. After all, yuppies were all about accumulating wealth, wealth, and more wealth. There's a definite math to the process of getting stinkin' rich.

But Charlie, as we've mentioned, fails on the math front. Could this be a little social commentary on the fate of yuppism as a whole? You be the judge.