Decimal variables are stored as 96-bit (12-byte) signed integers scaled by a variable power of 10. The power of 10 scaling factor specifies the number of digits to the right of the decimal point, and ranges from 0 to 28. With a scale of 0 (no decimal places), the largest possible value is +/-79,228,162,514,264,337,593,543,950,335. With a 28 decimal places, the largest value is +/-7.9228162514264337593543950335 and the smallest, non-zero value is +/-0.0000000000000000000000000001.
Note At this time the Decimal data type can only be used within a Variant, that is, you cannot declare a variable to be of type Decimal. You can, however, create a Variant whose subtype is Decimal using the CDec function.