Lommeregner

Lommeregner, Danish for pocket calculator, is a compact electronic device designed to perform arithmetic operations and increasingly more advanced mathematical functions. Most models fit in a pocket and run on batteries or solar power. They range from simple four-function devices to scientific and graphing calculators used in education, engineering, and business.

The development of pocket calculators accelerated in the 1960s and 1970s with advances in integrated circuits. Early units were expensive, but prices fell quickly as semiconductor technology improved. In the early 1970s companies such as Sharp, Canon, and Texas Instruments introduced portable models that could perform basic operations, with more capable scientific and programmable calculators following soon after. By the late 1970s, pocket calculators became common in schools and workplaces.

Types and features vary by use. Basic pocket calculators offer addition, subtraction, multiplication, division, and percentages. Scientific calculators add functions for trigonometry, logarithms, exponentiation, roots, and statistical calculations. Graphing calculators, typically larger, can plot functions and support more advanced programming. Financial calculators include features for interest, loans, and cash flow analyses. Many devices use liquid crystal displays (LCDs) and solar cells or replaceable batteries; some models support programmable functions or reverse Polish notation (RPN) input.

Impact and relevance have evolved with technology. Pocket calculators facilitated quick, reliable arithmetic across education, science, and business, reducing reliance on slide rules and manual computation. In the smartphone era, dedicated lommeregner remain common for their simplicity, independence from network connectivity, and durable, purpose-built interfaces.