A double precision floating point datatype. Numbers of this type are stored using 64 bits, they require more memory than numbers of type single, which use 32 bits. However, because they are stored with more bits, numbers of type double are represented to more precision than numbers of type single. The double-precision (or double) data type is represented according to IEEE Standard 754 for double precision. A value is formatted with bit-fields for sign, mantissa and exponent.