n! is called a factorial.
It would look something like this: n! = 1·2·3·...·n
An example:
5! = 1·2·3·4·5 = 120
Well I’m not 100 percent sure but I believe it’s b
This is a well known joke:
Why six afraid of seven? Because seven ate nine!
It is supposed to be a "word game" where instead of writing eight, the authour wrote ate, which sound the same but means something different.
Hope it helped,
Happy homework/ study/ exam!