Sindarin 

nelchaenen

ordinal. *thirtieth

A word appearing as nelchaenen “thirty” in the King’s Letter from around 1950 (SD/129), but more likely an adjectival form meaning “✱thirtieth”. Compare tolothen “eighth” from the same document based on toloth “eight”.

Neo-Sindarin: For purposes of Neo-Sindarin, I would use ᴺS. nelphaen for “thirty” based on later pae(n) “ten”. As an adjective I would use nelphaenui “thirtieth”; compare paenui “tenth”.