# Factorial (!)

Factorial[n]
n!
computes the factorial of n.

• 20!

Factorial handles numeric (real and complex) values using the gamma function:

• 10.5!

• (-3.0+1.5*I)!

However, the value at poles is ComplexInfinity:

• (-1.)!

Factorial has the same operator (!) as Not, but with higher precedence:

• !a! //FullForm