The digits in the Social Security number allow for the orderly assignment of numbers. The number is divided into three parts: the area, group and serial numbers.

The first three (3) digits (area) of a person's social security number are determined by the ZIP Code of the mailing address shown on the application for a social security number. See Social Security Number Allocations for more information.

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. After all numbers in group 98 of a particular area have been issued, the EVEN Groups 02 through 08 are used, followed by ODD Groups 11 through 99. Within each group, the serial numbers (last four (4) digits) run consecutively from 0001 through 9999.

Further information about Social Security Numbers that are currently assigned is available at High Group List and Other Ways to Determine if an SSN is Valid.