Efficient storage for BigDecimal in special cases.
- a 128 bit integer can hold a scale of up to 8 (4 bits) and a 120 bit mantissa
- commonly has a footprint of 32 bytes
- a 96 bit integer can hold a scale of up to 8 (4 bits) and a 84 bit mantissa
- commonly has a footprint of 24 bytes
- conversion methods between a long and a 64bit big decimal with 6 decimal places