If there's one number most people have memorized, it's their Social Security number. But most Americans don't know the hidden secrets behind those nine digits.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, unravels the mystery of the Social Security number. Dan notes that until recently, the first three digits pointed to the area of the office that issued the number. The middle two digits corresponded to sequential grouping, although the order in which those numbers were assigned included some interesting quirks.

Dan points out that now, though, Social Security numbers are randomized. That is helpful to prevent identity theft, but it presented challenges for financial institutions from Bank of America (NYSE:BAC) on down to the smallest local banks in verifying customer identities. With randomization, much of the mystique of the Social Security number has disappeared.

Fool contributor Dan Caplinger owns warrants on Bank of America. The Motley Fool recommends Bank of America. The Motley Fool owns shares of Bank of America. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.