To answer the question: as an American, I learned 12:00 AM was midnight at one point when I was a kid. Before then, I was unsure whether noon was 12 AM or 12 P

To answer the question: as an American, I learned 12:00 AM was midnight at one point when I was a kid. Before then, I was unsure whether noon was 12 AM or 12 PM. I made sure to remember that special fact, with no mnemonic or rationale, in the future.