system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is each lock and key combination unique, or do I share the same house key as a bunch of other people?

If I were to theoretically take the key to the front door of my house and try it on every other front door in the U.S., how many doors should I expect that key to open?
gpt
There are absolutely hundreds of thousands identical keys out there.

For example, a certain brand of door lock has 5 pins, each of which can be at one of 5 different settings. this means that for this brand there are only 3125 different keys made (5^5). if for example they made 1 million locks last year that means that if you bought one of those locks there would be 320 identical locks also sold.