A four-function calculator is one that only performs addition, subtraction, multiplication and division functions. Often, four-function calculators also have a square root, a percentage function, and an answer memory function (M+, M-, MS, MRC and/or MC).
Depending on the model, a scientific calculator usually includes exponents, logarithms (log, ln), trigonometric functions (tan, sin, cos,), and a reciprocal function. If your calculator has any of these functions, it is not allowed.
In addition to the functionalities of a scientific calculator, these calculators can have an entire screen rather than just a row of numbers that can display multiple calculations at once. With graphing calculators, data can be shown on the screen in the form of different types of graphs.
Your phone and your computer or laptop also have a built-in calculator. These are not allowed on the test.