2x9

2×9 is a notation used in mathematics to indicate either a multiplication or the dimensional size of a rectangular grid. In standard arithmetic, 2 × 9 equals 18. The expression represents the product of the integers 2 and 9, and, by the commutative property of multiplication, 9 × 2 also equals 18.

In number theory, 18 has divisors 1, 2, 3, 6, 9, and 18, and its prime factorization is 2 × 3^2. This factorization informs its multiplicative structure and helps explain the number’s divisors and multiples.

In geometry or everyday measurement, "2 by 9" describes a rectangle with side lengths of 2 and 9 units; its area is 18 square units if the units are the same on both sides. The phrase is commonly used in drafting, textiles, and construction to convey dimensions.

In linear algebra and computer science, 2×9 denotes a matrix with 2 rows and 9 columns, containing 18 entries. Such a matrix can represent a data set or be part of a larger computation, with its shape influencing possible operations, compatibility with other matrices, and computational costs.