numbers used as words
Solution 1:
It is called numeronym: a number based word.
From Wikipedia:
Less commonly, a numeronym is composed entirely of numbers, such as "212" for "New Yorker", "4-1-1" for "information", "9-1-1" for "help", and "101" for "basic introduction to a subject". Words of this type have existed for decades, including those in 10-code, which has been in use since before World War II.