Why do I keep getting an error message when I try to perform arithmetic or trigonometric calculations?
The error messages should indicate what the problem is. See the error message list in your calculator's user's guide for more information. Press the or key to display the location of the error. Other error messages may appear to let you know that a calculation you are trying to perform is not compatible with your current mode, angle unit, display, or other setting. If this happens, check the setup of your calculator and try again.