Twelve 

There is no reason to object to people spelling out the number twelve at FAC noms. Per Wikipedia:Numbers#Numbers as figures or words: "numbers greater than nine are commonly rendered in numerals, or may be rendered in words if they are expressed in one or two words". In the real world, twelve is almost never rendered as 12 in the middle of text as it is an extremely short word and there is no reason to convert it to a numeral to help readability.