Build a calculator that can add, subtract, multiply and divide decimal unsigned integers of up to 5 decimal digits. The calculator should have a display of 6 decimal digits. There should be a number pad with digits: o 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and five possible operators: o + (addition) o - (subtraction) o * (multiplication) o / (integer division) o = (equals) The flow of the operations should be as follows (as in a regular calculator): 1. While typing the number it should be displayed right aligned, extending to the left. 2. After pressing "+", "-", "*" or "/", display should be reset to empty, and the next number should be typed. 3. After typing the second number, "=" should be pressed and the display should contain the final result.

It can be design with logism.