To evaluate summation notation start by pressing the [math] key and then scroll to “summation” and press [enter]. Or press [math] and then press [0]. This will bring a textbook like display of a sigma template on your TI-84 Plus.

From there you will enter the summation notation template. Start by filling out your variable in the first box, the variable can be any single letter. Once you have done that, the calculator will automatically take you to the second box after you have filled out that box use the arrow keys to navigate to the next box.

Do not press [enter] until all of the boxes are filled out or you will generate an error. When you are done, press [enter] and your calculator will return the answer.