Is there any point in specifying the precision and scale of a number for a foreign key?
Connor MacDonald blogged about this over in NUMBER data type... what harm can it do? as well as Ask Tom: "How do I determine how much storage will be required for NUMBER(p, s)?". In short, it does matter.

Take this table:

CREATE TABLE T ( 
    x1 number,
    x2 number(6,3)
);


x1 will be 21 bytes while x2 will be 2 bytes. By not specifying the data type, you're taking up extra space that may not be needed.