Learning to use scientific calculators can be difficult if you aren't familiar with their basic operations. The Casio FX-83MS has specific modes for basic calculations, standard deviation and regression calculations. The calculator's display screen allows the user to input up to 79 characters on a single calculation, and has two separate lines for display. The FX-83MS also has specific buttons for performing trigonometric calculations, square roots, percentages, degrees and powers. Finding out about the basic rules for using the calculator can give you a good idea of how to perform the more complex functions.

Select your desired mode by pressing the "Mode" button followed by the number button "1," "2" or "3." Locate the four-way directional button, and then look to the right to find the "Mode" key. Hold this button and press "1" to enter the "Basic Arithmetic Calculations" mode. Hold this button and press "2" to enter the "Standard Deviation" mode, and press "3" in conjunction with the "Mode" button if you wish to perform "Regression Calculations."

Enter your desired calculations using the number keys and the operation buttons located on the bottom half of the FX-83MS's front panel. Use these buttons for all basic calculations, and add in more complex operations, using the keys on the top half of the calculator. For example, the trigonometric functions "sin," "cos" and "tan" are located on the second row of the black buttons, two rows above the "Del" and "AC" buttons.

Press "Left" or "Right" to navigate to a different location within the currently-entered calculation. The cursor icon (which is set as an underscore, "_") moves its position as you press the button. Navigate to the portion of the calculation you wish to delete and then press the "Del" button to delete it. Find the "Del" button by looking directly to the right of the "9" key. Press "Del" when the cursor is underneath the desired number or operation. Press "Shift" and "Del" to change the cursor to an "Insert" cursor. Move this box-shaped cursor over the number you wish to change and press the number you wish to replace it with. Find the "Shift" button in the top left-hand corner of the calculator. Press "=" to revert to the standard cursor.

Push the "Shift" or "Alpha" buttons in conjunction with another button to perform the operations printed above them. Look to the right of the "Shift" button to find the "Alpha" button. Note that the "Shift" label is written in yellow and the "Alpha" button is written in red. Hold these buttons and then press any other button to perform the actions printed above them in the same colour. For example, pressing "Shift" and "AC" will turn the calculator off, because "Off" is printed in yellow above "AC."

Press "Up" on the four-way navigational button to recall your previously-entered calculation and its result. Calculations are saved until you change modes or switch the calculator off or on. Pressing "Up" again continues to cycle through your previous calculations, from newest to oldest. Press "Left" or "Right" when a calculation is displayed to edit it.