I understand that this might be a loaded question.
For example, in Sql Server 2008, doing
DECLARE @someNum NUMERIC(10); means that the range of the variable will be limited by 10 digits. In other languages such as C, Java, etc. the standards for representing whole and fractional numbers are different. The range of the values is being sliced by multiples of bytes, and this is understandable, due to the way hardware works. A language could provide something that most hardware does not yet support, such as a 256-bit integer type, which will work fast on a 64-bit computer, if it is implemented correctly.
The numeric types in the databases seem to be not tied to underlying hardware. I understand that the values might need to be null-ablle, which can cost a bit or two, but why such arbitrary precision that does not seem to optimize storage or calculation speed?
Perhaps databases do not need to perform numeric computations often. Perhaps digit width of a column is a natural extension of character width. Perhaps SQL was supposed to be a non-programmers language (because it sounds like English :) )? Perhaps history took a weird turn, such as one that allowed the inferior VHS format to prosper.
Please help me understand this.