I know what the landlord means. He means, for example, 13, thirteen (from three), dreizehn (from german drei), the same eighteen, achtzehn, neuzehn, siebzehn, sechzehn and so on, while 1 1 660. Personally, I think an important reason is related to their beliefs or religions. Because many things in the world are related to 12, such as1February, 12 constellation, 12 zodiac (there are also Chinese zodiac sayings in the west). So they think the number 12 is more important, so they list it separately with 1 1

Just a personal judgment. If there is anything wrong, please point it out ~ ~