A calculator is a device that performs arithmetic operations on numbers. It is an electronic or mechanical device which is used for the performance of mathematical computations.

There are mainly two types of calculators. One is the simple calculator and the other one is the scientific calculator. The simplest calculators can do only addition, subtraction, multiplication, and division. The sophisticated calculators can handle exponential operations, roots, logarithms, trigonometric functions, and hyperbolic functions. Internally, some calculators actually perform all of these functions by repeated processes of addition.

Most calculators these days require electricity to operate. Portable, battery-powered calculators are popular with engineers and engineering students.

Theoretically, a modern computer is a calculator that works with binary numbers and has a much larger memory. But in the practical sense, a computer is far more than a mere calculator, because of the wide variety of non-computational tasks it can perform.