Undoing on a TI-84 calculator allows users to reverse their last action, restoring the calculator to its previous state. To undo an action, simply press the “2nd” key followed by the “Del” key. This will undo the last command or entry made on the calculator.
The undo function can be extremely useful for correcting mistakes, especially when working with complex calculations or programs. It can also be used to experiment with different values or settings without having to re-enter all of the previous data.