Use the exact numeric types, numeric and decimal, for numbers that include decimal points. Data stored in these columns is packed to conserve disk space, and preserves its accuracy to the least significant digit after arithmetic operations.
The numeric and decimal types are identical in all respects but one: only numeric types with a scale of 0 can be used for the identity column.
The exact numeric types accept two optional parameters, precision and scale, enclosed within parentheses and separated by a comma:
datatype [(precision [, scale ])]
precision specifies the maximum number of decimal digits that can be stored in the column. It includes all digits to the right or left of the decimal point. You can specify a precision of 1 – 38 digits, or use the default precision of 18 digits.
scale specifies the maximum number of digits that can be stored to the right of the decimal point. The scale must be less than or equal to precision. You can specify a scale of 0 – 38 digits, or use the default scale of 0 digits.
Exact numeric types with a scale of 0 display without a decimal point. You cannot enter a value that exceeds either the precision or the scale for the column.
The storage size for a numeric or decimal column depends on its precision. The minimum storage requirement is 2 bytes for a 1- or 2-digit column. Storage size increases by 1 byte for each additional 2 digits of precision, to a maximum of 17 bytes.