This classic RPN (Reverse Polish Notation) calculator is a simple calculator for daily uses. The calculator features a four visible level stack,the total stack size has a total of hundred positions. A progress bar on the top of the screen shows you how the stack is full.

For now the implemented operations are; plus, minus, multiply, divide, opposite, inverse.

Other facilities like swap the first two number in the stack and  recall from the last operation the two arguments should simplify the life. The keyboard error are notified by a vibration.