Dare i numeri, possibly the most well-known among all these expressions, means "to go crazy". This idiom can be traced back to the old Neapolitan Smorfia, which is now known as lotto. The Smorfia is a number generating system revolving around the interpretation of dreams. The etymology of this term is controversial, although the most commonly accepted hypothesis links it to the name of Morpheus, the god of sleep in ancient Greece. Traditionally associated with the city of Naples, the Smorfia is also referred to as Cabala. Some theorists actually suggest a connection with the ancient Jewish Kabbalistic tradition. Each number is paired with a name or image. This system eventually gave rise to many idiomatic expressions.
The expression dare i numeri seems to be evoking the random association between numbers and images typical of Smorfia, therefore referring by analogy to someone uttering nonsense or engaging in some illogical behavior.
Two more popular Italian expressions can be traced back to the game of Smorfia.
La paura fa 90 - this expression literally means “90 is a scary number” and refers to the fact that the number 90 is typically associated with the image of a screaming, scary-looking person. In English this concept can be expressed by saying “fear makes you do unthinkable things”.
47 morto che parla - this expression was so popular in the 1950s that it became the title of a book by Ettore Petrolini and was then made into a movie starring one of the most famous Italian actors of all time, Totò.
Although most Italian idioms featuring numbers do not have an English equivalent, some of them do:
Mille volte - A thousand times
Una su un milione - A chance in a million
2 più 2 fa 4 - Put two and two together
More than ten Italian expressions use the number 4! To name a few:
Gliene ho dette quattro - I gave him a piece of my mind
Fare quattro chiacchiere - To have a chat
Fare quattro salti - To dance a little
Fare il diavolo a quattro - This expression dates back to the Middle Ages and medieval theater. Back then, the devil was a recurring character in most plays. Expected to constantly change in appearance, the devil had to juggle acting and costume changes. Consequently, the role of the devil was often played by several (up to four) different actors, who would wait for their turn behind the scenes. The expression fare il diavolo a quattro has become extremely popular over time, and refers to the aggressive attitude of someone who would be willing to do anything to achieve their goal.
When mentioned in idiomatic expressions, the number 2 often refers to a small, irrelevant amount of something. In the card game known as Briscola, the 2 of spades has no strategic value!
Dare il due di picche - To not accept someone’s courtship.
Contare come il due di picche - To not make a difference in a decision-making process. To be totally irrelevant.
Fare due chiacchiere - To chat a bit.