[Retric]

Math includes the study of non computable things. Also, Math includes chaos theory which is more than just a formal system.

EX: computable numbers are a subset of all numbers. http://en.wikipedia.org/wiki/Computable_number

[RockyMcNuts]

mostly kidding. but presumably the theorems about non-computable numbers are computable and therefore you're still working with computable things?