The Early Qenya Grammar (EQG) of the 1920s had ᴱQ. leminkainen “fifty” as a combination of ᴱQ. lemin “five” and ᴱQ. kainen “ten” (PE14/49, 83). In the Qenya Lexicon of the 1910s leminkainen was instead “23”, perhaps “*five and eighteen” (QL/82). Compare later specialized “eighteen” words like 1920s ᴱQ. hualqe and 1930s nahta, though generally in Tolkien’s later writings kainen was “ten”. Christopher Tolkien suggested “23” was his father’s age at the time leminkainen was first coined, likely in 1915 (LT1/246).

Neo-Quenya: Late in Tolkien’s life, Tolkien changed the Quenya word for “ten” to quëan or quain, which has been the basis for various neologisms for “ninety”: ᴺQ. lepenquëan or ᴺQ. lepenquain. I prefer to use ᴺQ. lepenquain for purposes of Neo-Quenya.