I can still recite my childhood best friend's phone number. 555-2847. I dialed it a thousand times from that wall phone in the kitchen. My fingers knew the pattern on the rotary dial before my brain did.
You knew everyone's number by heart. Your parents. Your grandparents. Your three best friends. The pizza place. The movie theater recording that told you showtimes. These numbers lived in your brain permanently.
Now I do not know my own wife's phone number. It is in my phone under her name and that is where it lives. If I lost my phone, I could not call a single person I know. That still feels strange to me.