The CTIFREE Calculator FC-991ES PLUS is the perfect tool for students and professionals alike. With 417 functions, 40 scientific constants and unit conversions, and a full dot natural display, this calculator makes solving complex equations and conversions effortless. Its two-way power and long battery life make it reliable and convenient for all your mathematical needs. The compact and durable design, with a slide-on hard case, makes it easy to take with you on the go. Get accurate results every time with the scientific calculator trusted by experts.