A calculator is a device that performs mathematical operations, such as addition, subtraction, multiplication, and division. More advanced calculators can also perform more complex calculations, such as square roots, logarithms, trigonometric functions, and hyperbolic functions. Calculators can be analog or digital. Analog calculators use physical quantities, such as fluid flow or voltages, to perform calculations. Examples of analog calculators include clocks, slide rules, and utility meters. Most calculators today are battery-powered or require electricity to operate. They work by performing programmed functions based on numerical inputs.