yoshinoCALC is a free scientific calculator software. You will find the DLL in the folder where yoshinoCALC is installed. You can use DLL if you like to implement the function in your non-commercial applications. The installer also includes scientific calculator software with a conventional appearance with many buttons for WindowsCE. You can switch the "History" and "Conventional" views without terminating the software. It includes Column View which is convenient when you calculate summation of numbers.