Decimal numbers that may be expressed as a fraction, the denominator of which is a power of ten. For example, the numerals formula_5 represent the fractions , , . More generally, a decimal with digits after the separator represents the fraction with denominator , whose numerator is the integer obtained by removing the separator. Expressed as a fully reduced fraction, the decimal numbers are those, whose denominator is a product of a power of 2 by a power of 5. Thus the smallest denominators of decimal numbers are The "integer part", or "integral part" of a decimal is the integer written
Decimal computer processors, and also the Intel x86 family have special instructions that support conversion to and from BCD. The Psion Organiser I handheld computer’s manufacturer-supplied software implemented its floating point operations in software using BCD entirely. All later Psion models used binary only, rather than BCD. Decimal arithmetic is now becoming more common; for instance, three decimal types with two binary encodings were added to the 2008 IEEE 754r standard, with 7-, 16-, and 34-digit decimal significands. The IBM Power6 processor and the IBM System z9 have implemented these types using the Densely Packed Decimal binary encoding, the first in hardware