factor Also known as a divisor, a number or variable that divides evenly into another number or algebraic expression. For example, the factors of 28 are 1, 2, 4, 7, 14, and 28. Although it is true that 28 is also divisible by the negative of each of these, "factors" is usually taken to mean only the positive divisors. Factorization, or factoring, is the decomposition of an object into a product of factors. For example, the number 15 factorizes into prime numbers as 3 × 5; and the polynomial x2 - 4 factorizes as (x - 2)(x + 2). The aim of factoring is usually to reduce something to basic building blocks, such as numbers to prime numbers, or polynomials to linear expressions. Factoring integers is covered by the fundamental theorem of arithmetic and factoring polynomials by the fundamental theorem of algebra. Integer factorization for large integers appears to be a difficult problem; there are no known methods for solving it quickly and, for this reason, it has formed the basis of some public key cryptography algorithms. Related category MATHEMATICS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |