I added a "Functions" section to README.md covering all six functions that math.js exports. Each has a one-line description and an example showing its result. It also has a one-line require snippet for importing them. Where it applies, the description notes the error thrown: RangeError for a negative exponent in power, TypeError for an empty array in the statistics functions.
I ran the example calls in Node and the outputs match what the README shows. There is no test suite or linter for this docs-only change, so I ran none. The change is committed.