Both Tested and Work Perfect!!! TI 83 Graphing Calculator (Lot of 2) + Guide Book Engineers Mathematicians Scientists Product Information The Texas Instruments TI-83 Plus graphing calculator is the tool of choice for engineers, mathematicians, and science professionals. With the right features, reliable calculations, and quality display, it has everything you need. You will be able to find the answers to complex mathematical problems quickly. Those new to using Texas Instruments graphing calculators will find these devices useful for math and science classes. The search for a versatile graphing model that utilizes FLASH is over. The TI-83 Plus Calculator has a simple and intuitive key layout. Calculations are fast and simple. Creating graphs can be complex and difficult to understand at times. The easy-to-use graphing interface on the TI-83 Plus Calculator makes the programming language easy to learn. This allows you to create conversion programs into which you can enter information to create graphs. This TI-83 can store and analyze up to 10 matrices at once. With its data storage, lists can contain up to 999 elements, giving you the ability to store equations and variables. Creating graphs and solving equations can be done incorporating different variables. You can pick and choose which variables to use and see how they change the graph. Equations, plots, and coordinates can all be viewed at the same time. A variety of different problems can be solved using the Texas Instruments graphing calculator. Multiple plot types are available, such as scatter, box-and-whisker, WY-line, histogram, and probability plots. This allows you to address many types of statistical and graphing problems with one calculator. Advanced analysis tools are also available on the Texas Instruments TI-83 Plus. You can access statistical and regression analysis, graphical analysis, and data analysis when needed. There are features that can be used for all different types of math. The large, clear LCD screen is easy to read and can display up to 12 characters and eight lines. The operating system and software are upgradable, allowing you to stay up to date with the latest new features. The Texas Instruments TI-83 Plus runs on three AAA batteries. Additionally, there is a lithium-ion battery as a backup. Having a backup source of power assures you're not at risk of losing your valuable information when you?re in the middle of calculations. There is also an automatic shut-off system to save energy. A hardcover is included that can be slid over the face of the calculator. The cover provides reliable protection when it is not in use. It measures 7.3 by 1 by 3.5 inches, making it small enough to keep in your backpack, briefcase, or purse. You can always have it handy if you need to use it on the go. It is portable enough not to be cumbersome when you travel. The Texas Instruments TI-83 Plus is the complete package for advanced problem solving. It is full of the features you need to make complex calculations, and the FLASH software makes it a snap. Students can use it for statistics, calculus, trigonometry, algebra, and engineering classes. Professionals can use it to store and view valuable statistics to complete projects and calculations.Only one of them comes with case cover. Shipped with USPS