Once the Numlock door has opened, the numbers re-shuffle themselves and the door re-locks to ensure security.
While this is probably not useful in a regular run-of-the-mill house, I would love this for my bedroom door to keep out pesky guests.
Implications - The Numlock is the new generation of security catered to the technologically advanced society in which we live. With its sleek appearance and advanced security tactics, it really can keep anything a secret. The bond-style door lock is worth its weight in gold for those who value their privacy.