Best Answer: See http://en.wikipedia.org/wiki/Social_Secu... The Social Security number is a nine-digit number in the format AAA-GG-SSSS. The number is divided into three parts. The Area Number, the first three digits, is assigned by the geographical region.Prior to 1973, cards were issued in local Social Security offices around the country and the Area Number represented the office code in which the card was issued.he number is divided into three parts. The Area Number, the first three digits, is assigned by the geographical region. Prior to 1973, cards were issued in local Social Security offices around the country and the Area Number represented the office code in which the card was issued.