Number is a pretentiously-named library which provides functions to convert numbers into a variety of different formats. Ultimately, it aims to be a partial or complete clone of ActionView::Helpers::NumberHelper from Rails.
If you want to import all of the functions provided by
use it in your module:
defmodule MyModule do use Number end
More likely, you'll want to import the functions you want from one of
defmodule MyModule do import Number.Currency end
Number's behavior can be configured through Mix. Each submodule contains documentation on how to configure it.