What is the default Precision and Scale for a Number in Oracle?

Solution 1:

NUMBER (precision, scale)

If a precision is not specified, the column stores values as given. If no scale is specified, the scale is zero.

A lot more info at:

http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/datatype.htm#CNCPT1832

Solution 2:

The NUMBER type can be specified in different styles:

                Resulting  Resulting  Precision
Specification   Precision  Scale      Check      Comment
―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
NUMBER          NULL       NULL       NO         'maximum range and precision',
                                                 values are stored 'as given'
NUMBER(P, S)    P          S          YES        Error code: ORA-01438
NUMBER(P)       P          0          YES        Error code: ORA-01438
NUMBER(*, S)    38         S          NO

Where the precision is the total number of digits and scale is the number of digits right or left (negative scale) of the decimal point.

Oracle specifies ORA-01438 as

value larger than specified precision allowed for this column

As noted in the table, this integrity check is only active if the precision is explicitly specified. Otherwise Oracle silently rounds the inserted or updated value using some unspecified method.