What is multiple-precision arithmetic?
It is arithmetic carried out in software at higher precision than provided by hardware. Since the mid-1980s, essentially all new desktop and smaller computers have implemented arithmetic as defined by the ANSI/IEEE 754-1985 Standard for Binary Floating-Point Arithmetic, usually abbreviated to IEEE 754. This provides for 32-bit, 64-bit, and optionally, either 80-bit or 128-bit formats. These encode a 1-bit sign, a biased power-of-two exponent (8, 11, 15, and 15 bits respectively), and a significand (24, 53, 64, and 113 bits respectively) capable of representing approximately 7, 15, 19, and 34 decimal digits respectively. Although the IEEE 754 hardware precisions suffice for many practical purposes, there are many areas of computation where higher precision is required.
