Math works as long as you assume the numbers are just conceptual. Once numbers are mapped onto physical things, a lot of math just fails to model perceived reality. You can't actually have negative something. Most things can't be divided, and even if they can, don't divide evenly. Multiplication applies to fungible objects and little else. Imaginary numbers are, well, imaginary.

This isn't to say that complex math models are useless, just that the models may not work as expected when applied to the stuff that matters.