I don't really see how this is different from "LLMs can't multiply 20 digit numbers"--which btw, most humans can't either. I tried it once (using pen and paper) and consistently made errors somewhere.
People made missiles and precise engineering like jet aircraft before we had computers, humans can do all of those things reliably just by spending more time thinking about it, inventing better strategies and using more paper.
Our brains weren't made to do such computations, but a general intelligence can solve the problem anyway by using what it has in a smart way.