A computer numbering format in which a number occupies two storage locations in computer memory (called “address[i]” and “address[i]+1″). A double precision number, sometimes called a double, may be an integer, fixed point, or floating point. The term double precision is not truly accurate because the precision is not really double. The word “double” simply means that a double-precision number uses twice as many bits as a regular floating-point number. For example, if a single-precision number requires 32 bits to define, its double-precision counterpart will be 64 bits long.
Computers with 32-bit data stores (single precision) provide 64-bit double precision, in a series of 8-byte words. Most applications conform to an IEEE standard (754) that defines the encoding of floating-point numbers using 8 bytes.