This RPN calculator offers a choice of more than 200 solutions with five unique keypads. It has a complete help system with individual tips for all but the most ordinary functions and a Tip of the Day feature for new users. You can choose between fixed, scientific and engineering notation and select degrees or radians as required. You can save (great for returning to a task) and print the contents of the running tape display. The functions available using any keypad are, Lastx, retrieves the last number that was used in a calculation, Drop, deletes the current value in the x-reg and Drops the number in the y-reg into the x-reg, greater-than and less-than, exchanges the values in the x-reg and y-reg, STO, which can save up to 4 numbers into memory (the 'm' key), 2 of these storage registers can be used for register arithmetic, x-squared, square root of x, 1/x, and 8 constants involving pi. Standard. Engineering and Trig keypads also have a convenient function to convert between polar and rectangular coordinates. Briefly, unique to the 5 keypads are: Standard ? contains several of the functions found on a normal scientific calculator (log, ln, N!, etc.), and some unique to itself: a simple math teaching aid for kids, Wind Chill calculator, and more. Engineering ? handles problems like Resonant Frequency, Ohms Law, Parallel Complex Impedances, Polynomial Equations, Impedance of a Ladder Network, and lots more. Magnetics ? eases the design of transformers and inductors with many built in functions unique to magnetic component design. Engineering and Magnetics offer selecting units used in many of the calculations. Trig ? solves Arc Length, Right Triangle, and any Defined Plane Triangle problems, also computes the trig functions, as well as some hyperbolic functions. Converts Radians to Degrees, and Hours, Minutes, Seconds to Decimal Hours and vice versa. Convert ? thousands of conversion possibilities including between decimal and binary, octal, or hexadecimal numbers, + more than 40 constants.