Why the increasing emphasis on decimal arithmetic?
Most people in the world use decimal (base 10) arithmetic. When large or small values are needed, exponents which are powers of ten are used. However, most computers have only binary (base two) arithmetic, and when exponents are used (in floating-point numbers) they are powers of two. Binary floating-point numbers can only approximate common decimal numbers. The value 0.1, for example, would need an infinitely recurring binary fraction. In contrast, a decimal number system can represent 0.1 exactly, as one tenth (that is, 10-1). Consequently, binary floating-point cannot be used for financial calculations, or indeed for any calculations where the results achieved are required to match those which might be calculated by hand. See below for examples. For these reasons, most commercial data are held in a decimal form. Calculations on decimal data are carried out using decimal arithmetic, almost invariably operating on numbers held as an integer and a scaling power of ten. Until recently,
