Factorials.

The n! button in formula entry notation mode calculates the factorial of a number. A factorial is the result of multiplying all the numbers from a given starting point down to one.

Note: You can use factorials to find the number of ways things can be arranged. For example, if you want to find possible anagrams of a word with four letters, 4! shows that there are 24 ways these letters can be arranged.

• To find the factorial of a number in formula notation mode: enter the number for which you want to find the factorial, press the n! key and press Enter.