From Judy's Applications:
Judy's TenKey enables you to work faster and more reliably. Once you can see (and reuse) the numbers in your calculations, you will never return to the default Windows calculator. If you're still using an old-fashioned desktop calculator, you'll love the integration Judy's TenKey gives you with your other Windows applications. Judy's TenKey provides nearly every feature imaginable, yet makes your experience simple and effortless.
TAPE: Records your calculations in a scrolling list which you can annotate, save, print, and resize (a real help in keeping track of your calculations). You can also modify tape entries, causing the tape to recalculate, or reuse previous entries in new calculations (saving typing and reducing errors).
FLEXIBILITY: Judy's TenKey can process numbers like a scientific calculator (RPN), an adding machine, or a normal calculator. If you are familiar with one and not another, you know how difficult and frustrating it can be to try to switch.
AND MORE: You can configure your TenKey display, selecting from tape, memory, statistics, functions, trignometry, finance, and number pad options. Supports automatic decimal insertion, auto-numlock, dedicated keyboard calculator key, red negative numbers, international formatting, item counter 'keep on top' for immediate access, and 'Tip of the Day' feature. Remembers your favorite screen position and displays itself there every time.