system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do currency counting machines only grab one bill at a time so quickly and accurately?

It drives me nuts wondering how these machines are able to do this so fast when i have trouble grabbing just one bill using my hands!
gpt
They use rollers with a rubbery surface that grab one bill from the bottom of a stack (just like your printer does with sheets of paper). AFAIK there are also models that have a light shine through the bills to detect if more than one bill was grabbed.