Oh, and the letter parts are not what you need to give the cashiers if you’re calling in an order. The number you’re looking for to ensure ease of purchase is going to start either with a 6, a 66, or a 68. And although most of them end in 00, a few of them that are pairs or left/right stamps end in -01,-02, -001, or -002.
Sometimes you might get lucky and find someone who has aaaaalll the letters and number sequences memorized, but kindness asks for the 6.....-... number.