Clac98 is a free engineering, scientific and financial calculator for Windows. The calculator includes functions for statistics, use of different number bases (binary, octal, hexadecimal and base-n), metric units conversions and physical properties and constants. It has financial functions including investment, loan and mortgage calculations. It also calculates time functions and has a stopwatch feature and RPN (Reverse Polish Notation). It runs on Microsoft Windows (WindowsNT, Windows95/98/ME, Windows2000/XP) and WindowsCE (Pocket PC).
You may use Calc98 for 90 days then that authors ask that your register the product, for free.