Enter an expression such as 4 (4 + 4) - 2 x (- 5) = by entering "4," "(" then "4 + 4" then ")" then "-" followed by "2," "x," "(" then "-" and then "5" followed by ")" and then "=." The calculator will perform the calculation.
Input some functions by pressing the dedicated expression button on the calculator if there is one. For example, press "Sin." The calculator will display "Sin" and the opening parenthesis. All you have to do is add the argument and closing parenthesis. For example, if you press "Sin" and then "3" and then "0" and ")" and then "=," the calculator will determine that "Sin" is the function and will automatically add the opening parenthesis to make "Sin(30)=" the answer would be "0.5" and displayed.
Look on the calculator keypad for the functions like "Cos," "Tan" and so on. Sometimes the function is entered with an alternate key. For example, sometimes you may have to press the "Shift" or "2nd" key to get the alternate button usage. The function will be printed on the calculator's cover adjacent to the button as opposed to imprinted on the button. It will often be color coded with the "Shift" or "2nd" key.