How do I find my Mac's PIN? I swear I've never created one for my Macbook.

Hi qwerty583,

Thanks for reaching out in Apple Support Communities. I understand you're being prompted to enter a PIN number for your MacBook and you're not sure when it was created or what it could be. I know it's important to have access to your Mac; I'd like to help. It sounds like you're describing a system lock PIN code:

"System lock PIN code

Your Mac asks for a PIN code when it has been remotely locked using Find My. Enter the four-digit or six-digit passcode to continue."

About the screens on your Mac as it starts up

To access this passcode, you'll need to follow these steps:

"How do I unlock my Mac?

Here's how to see the passcode that you used to lock your Mac:

1. 1. Sign in to icloud.com/find. 
   2. Select your Mac from the Devices menu. 
   3. Select Unlock. After you follow the steps to verify your identity, you'll see the passcode that you need to unlock your Mac.

You can look up your passcode for a limited time. If you forget your passcode or can't verify your identity to see it, take your Mac to an Apple Authorized Service Provider along with your proof of purchase."

If your Mac is lost or stolen

Best Regards.