This is an RPN (Reverse Polish Notation) calculator with many useful features. The RPN expression evaluation is superior to Algebraic. There is a four register stack and ten memory locations for number storage. A preview of the register stack is shown at the lower left corner of the display and is extremely helpful in getting used to RPN. This calculator contains many useful functions. These include the normal scientific functions like trigonometry, logarithmic and others. It has a graphing capability with includes a linear, parabolic, and polar modes. You can graph equations, integrate between limits on an equation, find the roots and graph polar equations. There is a date calculator, an amortization section, which allows exportation to an email. It has a matrix function where you can invert, multiply, add or subtract matrixes. There is a cleaver converter and even a hexadecimal section that also works in octal and binary. A gas constant function has been added along with a Period Table lookup function. There is extensive help available witch is context sensitive too. In addition, much attention has been given to the use of an external bluetooth keyboard in all sections of the calculator. In short, this is a very useful calculator and can do complex arithmetic functions, but it is also very handy at doing just simple arithmetic.