1. The red buttons on the calculator represent the numbers "0–9". Click on these buttons to type any number. 2. The blue buttons are the "operators": * for "addition" - for "subtraction" × for "multiplication" ÷ for "division" 3. After entering the numbers and selecting an operator, type another number and press the "=" button. The result will appear on the top screen. 4. If you make a mistake or want to start over, press the "C" button.