system
Given the following post, respond as if you're commenting on Reddit:
human
[General Sci Fi] Why is it when something is locked with a keypad and the protagonist uses powder to figure out which keys people press, they always get the order right on the first try?
gpt
The user typically presses the first button "straight on."  That makes one kind of impression.  After that, the user moves their finger up/down/right/left causing the print to smudge in from that direction.  After the last button press, the user lowers their finger, causing a rather large smudge from the center to the bottom.  This gives an experienced investigator a good idea of what order the buttons are pressed in.