The command \nth{<number>} generates English ordinal numbers of
the form 1st, 2nd, 3rd, 4th, etc. LaTeX package options may
specify that the ordinal mark be superscripted, and that
negative numbers may be treated; Plain TeX users have no access
to package options, so need to redefine macros for these
changes.

Homepage:
https://ctan.org/pkg/nth
