Dim Value As Double
A Double is a signed 64 bit floating point data type. Like the Single, it is stored internally using a little-endian IEEE 754 memory layout and the same precautions regarding precision should be taken. A Double can store integer values in the range of -9,007,199,254,740,992 to 9,007,199,254,740,992 without a loss of precision. The precision of floating point numbers depends on the exponent.
A Double will overflow if assigned a value greater than roughly 21024. It will not overflow with negative exponents, although the usable precision will be questionable before the upper limit is reached.
The casting function to convert to a Double is