Need a calculator to perform simple calculations? The Windows 8.1 calculator is a free calculator that performs the basic functions of a calculator, while giving off the vibe of a real calculator. We have added extra buttons and functions! The Windows 8.1 calculator just got more functional with new scientific functions. Let us know how you like the app by rating our app or liking us on Facebook! We'd love to hear your thoughts and what to improve on the app.