Matrices are rectangular arrays that contain numbers or elements. Matrices can be stored on a TI-84 graphing calculator to perform matrix operations on the calculator. Common matrix operations are addition, subtraction and multiplication with a scalar. When you no longer need a matrix, clear it out of the memory on a TI-84.
Press the "2nd" key and the "+" key on the TI-84.
Scroll to "Mem Mgmt/Del."
Press the "ENTER" key.
Press "5" to select "Matrix" and press the "ENTER" key.
Scroll to each matrix and press "DEL." This will clear the matrix out of the memory. Each matrix will look like "[A]" in the calculator, except it may have a different letter associated with it.