find replace

[0-9]{4} means "four digits in a row" — a character class matching any digit, repeated exactly four times by the {4} quantifier. The < > markers force a whole word, so a longer number such as 15 000 or a code like 20231 is not partly matched; without them, the middle four digits of a longer number would also match, which is the opposite of what "four-digit years" means. Marks: wildcard search for four digits, green format, Replace All. Doing it by hand would miss instances in footnotes and citations — exactly the kind of place a human skim-read overlooks but a pattern search does not. An alternative without wildcards: Find ^#^#^#^#, Word's own (non-regex) shorthand for "any digit," repeated four times.