Kertolaskenta

Kertolaskenta, or multiplication, is the arithmetic operation that combines two or more numbers, called factors, to produce a product. It is a fundamental operation alongside addition, subtraction, and division and is used across mathematics, science, engineering, and daily life.

In mathematics, multiplication has several key properties. It is commutative: a × b = b × a; associative: (a × b) × c = a × (b × c); and distributive over addition: a × (b + c) = ab + ac. The identity element is 1, since a × 1 = a, and any number multiplied by 0 yields 0. Factors and products can be integers, fractions, decimals, or more general numbers in advanced contexts. Notation varies: in written form, the times sign × is common; in programming asterisk * is often used; in algebra, multiplication is frequently written by juxtaposition (ab).

Methods and representations for computing kertolaskenta include repeated addition, the area model, lattice multiplication, and the standard long multiplication algorithm. In computer science, binary multiplication underpins algorithms and hardware. Understanding multiplication also supports other concepts such as powers, exponents, and algebraic factoring.

Education and usage: kertolaskenta is introduced in elementary education and reinforced with visual models, mental strategies, and increasingly abstract rules. It underpins recipes, budgeting, measurements, geometry (areas and volumes), and data scaling. In Finland and many countries, it is a core part of early math curricula, emphasizing understanding of properties and reliable computation.

History: Multiplication has roots in ancient civilizations and evolved through techniques such as repeated addition, Egyptian and lattice methods, and later standardized notation in early modern mathematics.