How do you enter a variable in a TI-84 plus calculator?

Answer 1

To enter an equation variable, (for example X when you are in function mode, or theta when you are polar mode), press the X, T, θ, n button.

To enter a different variable, press ALPHA and then the letter of the variable. For example, to enter the variable C, press ALHPA C (above PRGM). These non-equation variables act as constants. To set the value of constant C to 3, for example, enter 3

-> C and press ENTER. (The arrow is the STO> button).

Answer 2

To enter a variable such as X, press the X,T,θ,n button. To enter another variable such as A (these variable just store numbers) press ALPHA and then the button with the letter you want over it.