This Programmable RPN calculator has 6 unique keypads (see below) and 15 discrete calculators for the more complex functions. 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. Select fixed, scientific or engineering notation and degrees, radians, or grads. Save and print the contents of the running tape display. There are 24 storage registers that can be identified by name, and it is now programmable, using the easy to learn RECPL (RPN Engineering Calculator Programming Language). Functions available from any keypad: REG, for manipulating the storage registers (2 of these are used for register arithmetic); Lastx, recalls the last number used; Drop, deletes the number in x-reg and Drops the number in y-reg into x-reg; exchange the values in the x-reg and y-reg; xÂ²; square root of x; 1/x; and 8 constants involving pi. Some keypads also have a function to convert between polar and rectangular coordinates. Briefly, unique to the 6 keypads are: Standard; 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. Binary; is used to manipulate unsigned Binary integers of various lengths (word size) from 4 to 64 bits, about 22 functions are available. Magnetics; for the design of transformers and inductors with many built in functions unique to magnetic component design. 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 conversions, more than 40 physical constants and many specific gravities.