All modern United States currency contains either a 10- or 11-digit serial number in order to make each bill unique. Ten-digit serial numbers were on all bills until the "new style" came out in 1996. Those bills (and all produced since then) have an 11-digit serial. The serial number consists of the following: … [Read more...] about Why Do Some U.S. Bills Have a Star at the End of the Serial Number?
