The Casio brand has been at the forefront of desktop calculators since the electronic era stepped into the "Calculator Wars" back in the early 1960s. Casio was a driving force in the market then and continues to thrive today. The MS-80VER model is a good example of a simple yet very useful calculator.

Key in a number, press the add (+) button and key in another number. Continue until you've keyed in the final number and press the equals (=) button to get the sum of a series of numbers. Note that every time you press the add (+) button, you will see a subtotal of the previously entered numbers on the display.

Enter a number and press the subtract (-) button, enter another number and the calculator will perform a subtraction operation. It works just as the addition feature in that it displays a subtotal of all numbers previously subtracted. Hit the equals (=) button to get the final result of your calculation.

Multiply two or more numbers simply by pressing the multiply (x) button after entering each number. To get the final result press equals (=). The division function works in the same manner using the division symbol key (÷), instead of the multiply key.

Calculate percentages easily by using the percentage feature. For example to get 30 per cent of 1000, simply enter 1000 then press multiply (x), key in 30 and press per cent (%).

Press the "AC" or "C" button to clear the entry if you made a mistake while performing a calculation.