Factorial
The factorial feature is found by pressing
and then selecting PRB.
To calculate 5! type 5
and press
three times to select PRB. Then, select ! by pressing
followed by
.
and press 
three times to select PRB.
Then, select ! by pressing 
followed by 
.
and then selecting PRB. and press three times to select PRB.
Then, select ! by pressing
followed by .