Use "2nd" in prose

Warning²Federal courts, Illinois courts21st and 22nd editions

Running prose spells out a hundred-or-greater ordinal ending in two or three as “102nd” or “103rd”; the clipped “102d” and “103d” form belongs only to citations.¹

1. 1R. 6.2(b)(ii) Ordinals. Tables: R. 6.2(a) Numerals.
2. 2A warning: the form is usually wrong under the rule in note 1, and context can justify it.