Acron RPN Calculator
Don't let the simple interface fool you, this calculator is packed with features. Beautiful rendering of both the question and answer make your calculations virtually foolproof. Built in symbolic manipulation gives you the mathematically perfect answer to most common computations, with a fall back on 64 bit floating point approximations to handle the nastiest math. Supports integer calculations in binary, decimal, and hexadecimal for byte, word, dword, and qword integers. Calculate one and two variable statistics with four available regression models. Macros make it easy to repeat calculations without any programming skills.
There is also a free version of Acron RPN Calculator. It has no ads, and never expires, but does have the following limitations: