How to Evaluate Factorials on the TI-84 Plus - dummies

By Jeff McCalla, C. C. Edwards

Did you know you can type an exclamation point on your TI-84 Plus calculator? Mathematically, the exclamation point is called a factorial. Usually students learn about factorials in pre-algebra and then forget what they are by the time they need to use factorials to solve tough probability problems. Here is a quick refresher on factorials.

4! = 4*3*2*1 and 7! = 7*6*5*4*3*2*1. If you haven’t done so already, press [2nd][MODE] to get to the Home screen. Follow these steps to type a factorial in your calculator:

  1. Enter the number you would like to take the factorial of.

  2. Press the following keys to access the Math Probability menu


    and press [4] to choose the factorial symbol (it looks like an exclamation point.)

    There are more MATH submenus available on the TI-84 Plus C, if you use the TI-84 Plus, pay attention to the name of the submenu and use the left- and right-arrow keys to navigate to the correct one.

  3. Press [ENTER] to evaluate the factorial.