Within each area, the group number (middle two (2) digits) range from 01 to 99 but are not assigned in consecutive order. For administrative reasons, group numbers issued first consist of the ODD numbers from 01 through 09 and then EVEN numbers from 10 through 98, within each area number allocated to a State.umber Has Three Parts. The nine-digit SSN is composed of three parts: 1  The first set of three digits is called the Area Number. 2  The second set of two digits is called the Group Number. 3  The final set of four digits is the Serial Number.