What is the value of 2!?

Fill in the blank: 

 3 × 2 × 1= ________.

  Fill in the blank: 

1! is defined as________.

 Fill in the blank:

_____________is used to represent the product of all positive integers from 1 to a given positive integer.

What is the value of 3!?    

  What is the value of 7!?

  Fill in the blank: Factorial is denoted by_______________.

Fill in the blank: 0! is defined as ________.

 What is the value of (-1)! ?

Fill in the blank: 

5 × 4 × 3 × 2 × 1= ________.