This is more how an LLM thinks about math internally - an LLM version of drilled tables being used for mental arithmetic "as humans do".

When humans stall on these tasks, they reach for pen and paper, a slide rule, a calculator, etc.

Mathematica is overkill for arithmetic, in addition it's licenced and can cost a bit extra.

If an LLM were to reach for a light cheap arithmetic tool something like bc would be a good first stop - a CLI tool with a language that supports arbitrary precision numbers with interactive execution of statements.

https://en.wikipedia.org/wiki/Bc_(programming_language)