MPCalcRB is a multi-precision RPN calculator built using Xojo and the developer's MPCalc Plugin. It can handle numbers with up to 30,000 decimal digits. As floating point numbers, the magnitude of the exponent can be very large, of the order of 40,000,000 or so. In addition to the usual mathematical functions there is support for Bessel functions, Error functions, Fresnel integrals, etc. The Help menu describes them.