Random little thing I noticed while comparing my Amtrak tickets.
My reservation code looked something like C35266 (not the real one). On the QR code it showed up as something like C35266-08MAR26, which seemed normal.
But the PDF417 barcode on the physical ticket had a long number like 1280061420260308. At first it just looked like random digits, but the last part clearly matches the booking date (20260308).
Then I realized the first part actually isn’t random at all. If you take the reservation code C35266 and treat it as a hexadecimal number, converting it to decimal gives 12800614, which matches the beginning of the barcode.
I guess that’s also why reservation numbers only use A–F for letters.
Funny how I never noticed that before.
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