I got a new (to me) Honda Civic after my truck finally started leaking fluids everywhere. Buying used cars always involves fixing issues and one I had was the passenger door lock being keyed different. I found this video on youtube showing how the tumblers are numbered. While I had the driver side off replacing a broken handle I got the numbering sequence and fixed the passenger side lock. It’s really simple and a cool trick I wnated to pass along.