Turn on your TI-83 calculator. Press the clear button to erase any old equations from the screen.
Press the "Program" button, and select "New" from the top of the screen options. Next, press the "Add" button and type in the desired name of your program. Press the "Program" button one additional time. This will prompt a list of command options to display on the screen.
Scroll through the options until you can select I/O. Press the Input option and press enter. Your screen will now display : input and say Variable A. Repeat steps two and three and type : input Variable B.
Press enter to begin a new line on the program code and select the DISP option. Enter Answer, A+B and press the second QUIT option to exit the programming screen. This program will enable you to perform simple addition on the calculator easily.