I was worried this would happen to me. I made an entry in my notes app. "Doctor Harry Bottomsmith 801-421-8623 9 am Friday" where 4218 was my PIN.

That's saved me a few times when I blanked out. This note, in theory, will look completely innocuous in case anyone gets access to my notes.

I've had a few of these. Until years later when I stumbled upon them again and totally forgot how they were meant to be decoded.

You just validated every adventure game player typing in whatever numbers they can find to try and guess passwords.

This is more generally known as steganography: https://en.wikipedia.org/wiki/Steganography

A year ago, I had to go to a bank office and engage in some verification process that also required me to use the physical bank card with its preassigned PIN.

No matter what I tried, I hit the 3-try limit for the day, and opted to have the same preassigned PIN sent by mail to my home address.

When walking back home from the bank branch I realized the mistake I had made: I had entered the correct PIN, but had typed it in calculator/numeric keypad order, and not in phone/PIN pad order.

While I've never used that PIN on a numeric keypad for a PC, somehow my brain associated the numbers with their order on a PC keypad, since I had used my PC keypad to unlock my PC with a PIN numerous times more than I had used any card terminal with a PIN.

So, the next day, I returned to the bank branch office to try the same operation again, and indeed - I had correctly entered the PIN and the online banking transfer limit ended up adjusted just fine.

For the past decade and a half, possibly longer, Japanese ATMs have replaced their physical keypads with digital ones where the numbers are randomly placed. Imagine my surprised when the first times I tried to enter my PIN, it kept failing until I took a good close look at the numbers.

Had the same experience. Went to an ATM one night and the PIN for my card that I'd used several times a week for probably a decade was just... gone. Never before, never since.

I once forgot root password to my FreeBSD installation, I spent a lot of time trying to remember it but failed. So I did a reinstall, and obviously recalled it when prompted to come up with a new one.

This happened to me last year.

Completely out of the blue I forgot my PIN, the PIN I had used every day for years. I was at an ATM trying to withdraw cash, got it wrong twice. It was just gone.

Luckily I cancelled it before the machine ate it, but I had to borrow money from someone to get a taxi home.

I had to request a new PIN and I still can't remember what it was. I now keep my pin in my phone under a contact.

I’ve had the same experience. Walked up to an ATM for the second time in two days and my 4-digit PIN was simply gone from my memory. I never figured out what it was.

That was almost 30 years ago, and thankfully it hasn’t happened again.

I use my ATM so infrequently that it's happened to me a few times. I get cash reups selling stuff on Craigslist so I need the ATM like once a year. Luckily my ATM is right next to an in grocery store branch so resetting the pin is 3-5 minutes talking to someone irl

I've had this happen to me multiple times, and more often now that so much payment is contactless here (even though I still have the same code as when it wasn't). Additionally, something as simple as a different machine (the most recent instance was a touch screen) can throw me off as well.

I went for a week holiday and when I came back I couldn't remember the alarm code. Had to call the boss at 7am with the alarm blasting in the background.

It has already happened to me blank on the 4-digit PIN I have since more than 5 years. Never thought I could forget something so short I use so often.

Some bank cards have allowed you to change the number to a more memorable one.

The other thing you can do is make a mnemonic story to help you remember it.