DEC64 is a number type. It can precisely represent decimal fractions with 16 decimal places, which makes it very well suited to all applications that are concerned with money. It can represent values as gargantuan as 3.6028797018963967E+143 or as measly as 1.0E-127, which makes it well suited to most scientific applications. It can provide very fast performance on integer values, eliminating the need for a separate int type and avoiding the terrible errors than can result from int truncation.