A four-function calculator (with square root) is permitted on both the multiple-choice and free-response sections of the AP Biology Exam since both sections contain questions that require data manipulation. No other types of calculators, including scientific and graphing calculators, are permitted for use on the exam. Four-function calculators have a one line display and a simple layout of numeric keys (e.g., 0–9), arithmetic operation keys (e.g., +, -, ×, and ÷), and a limited number of special-use keys (e.g., %, +/-, C, and AC). Simple memory buttons like MC, M+, M-, and MR may also be included on a four-function calculator. Scientific calculators have a more complicated, multi-row layout that includes various special-use keys, including ones for trigonometric and logarithmic functions such as SIN, COS, TAN, TRIG, LOG, and LN. In contrast to scientific calculators, four-function calculators do not include trigonometric and logarithmic functions, statistical capabilities, or graphing capabilities. Students may bring up to two four-function calculators (with square root) to the exam.