npub1808axrhpwt02nt0nnndlcndua3jjaaffxu63prv8p80dknn6s4ysldznwv (npub1808…znwv)
You go to some place, let's call it... Schmoodles and Schumpany.
There's a stack of gift cards. You pick one up and observe its number. 133769420
The one after that in the stack will be 133769421. The one sold yesterday is 133769419.
You can balance check ones before the one you observed, or wait a while and balance check the ones afterward.