e.g. 42
Spell them out like "forty-two".
(Was Footnote: the number 42) also works.
Syntax like (Was Footnote: 42) is the old way to link to a remote Wiki, before
the style (Was Footnote: URL) was supported, according to TextFormattingRules.
Writing this page as (Was Footnote: Why Does Not Wiki Do Numbers) would have been prefered to the !BumpyCase method, and it could then become (Was Footnote: Why Doesn't Wiki Do Numbers), which sounds less silly. On the editing page, btw, there is a little note that tells us: "!BiCapitalization looks silly, use brackets for links." See Guidelines for Links.