I just noticed I've got an interesting serial number. . . A repeater? $50 National Currency Note (1929 Federal Reserve Bank of Chicago) with serial G00167167A. The Note itself is well-worn (I'll post a picture if anyone's interested).
Cool serial number, and a repeater IF you don't count zeros.......otherwise not a true repeater. A true repeater would be G01670167A.
If your National Currency has 8 spots for digits and one of them is a zero you DO NOT have a repeater. Sorry.