Although the binary system has been the numbering system of choice in the design of modern computers since the first digital computer was built, decimal computation has grown to become a necessity.
Decimal is human intuitive and is more suited for representing monetary transactions. Decimal arithmetic provides a robust, reliable framework for financial applications that are often subject to legal and regulatory requirements concerning rounding and precision of the results in the areas of banking, telephone billing, tax calculation, currency conversion, etc.
On another hand, binary floating-point arithmetic that current computers’ hardware uses does not always satisfy the stringent accuracy requirements of some financial applications. The underlying cause is that most decimal fractions, simply said such as ‘0.1’, cannot be represented exactly in finite-precision binary floating-point format.