Final answer:
A door lock with a keypad of 5 buttons requires the correct sequence of button presses to unlock.
Step-by-step explanation:
A door lock with a keypad of 5 buttons requires the correct sequence of button presses to unlock. This is an example of a security mechanism based on logic and combinatorial possibilities. Let's say the correct sequence is 3-1-4-2-5. The door will only unlock if you press the buttons in this exact order. If you press any other sequence, the door will remain locked.