A four-function calculator is one that performs addition, subtraction, multiplication and division functions. Many such calculators have additional functions such as the square root and exponents.
A four-function calculator is the simplest type of pocket calculator and is suitable for basic arithmetic. Calculators with higher functioning abilities are either scientific calculators or graphing calculators, both of which can also perform the functions of a four-function calculator. Scientific and graphing calculators can perform computations on data sets and have built-in complex functions such as linear regression. In some math courses, scientific and graphing calculators are prohibited during exams because students are required to perform these complex functions without assistance.