A few days ago I needed to get into my parent’s house while they were on holiday. I was driving to my house to fetch their spare keys and fretting about having forgotten their alarm code. As I opened my front door the alarm keypad began beeping. I instinctively started punching in a code. As I was pressing the keys I became aware that the pin I was entering was not the pin for my house but a totally different pin.
When I pressed the last number I realised that he pin I had just entered was the pin for my parents house. A pin that I could not remember a few seconds ago.
Mind blown.
arbitraryuser 
You are not alone… That is exactly how I remember the last four digits of your phone number… Don’t ask me what they are, but I can punch them in on a keypad…
Oh…On that note…look at this:
http://theoatmeal.com/comics/brain